"Hong Kong was called a shopping paradise. I would say it's a shopping hell now." So says Raye Long, from Guangzhou, of buying infant formula for her 18-month-old son. She is frustrated by the city's new limit on exports of baby milk powder, introduced to crack down on parallel-goods traders and protect local consumers. The latest restriction reflects the tip of the iceberg. A plethora of issues bring mainland and Hong Kong residents into conflict - a problem for governments on both sides of the border. With his popularity flagging since taking office in July, Chief Executive Leung Chun-ying often appears to be walking a tightrope between pleasing the locals and allaying discontent across the border. Leung, who is in the capital today for the closing of the National People's Congress, might face a new round of pressure from state leaders. It is his second visit to the capital in as many weeks. "The new people in charge of the ministries and commissions will be appointed after the closing of the NPC session. I hope to have preliminary discussions with them on Hong Kong's future development and the [bilateral] work ahead," Leung said on Tuesday. Last week in Beijing, Leung denied that the two-can limit on milk-powder exports was a populist gesture to assuage public anger in the city. "Some families could not buy the milk powder their babies are used to consuming in the market, which was indeed troubling to them," he said. "So this is not a problem of populism." Parallel-goods traders, who buy goods in Hong Kong for sale across the border, taking advantage of lower prices and tariffs in the city, have been the target of popular anger, especially in the northern New Territories. Local protesters in Sheung Shui last year waved banners with the slogan "Chinese people, go back to China", which left many mainlanders disgruntled. The war of words has intensified, particularly after the rule preventing travellers leaving Hong Kong from carrying more than two cans, or 1.8kg, of infant formula out of the city in 24 hours, except with a licence, came into force this month. It leaves mainland mothers, many of whom doubt the quality of the infant formula available at home, struggling to get supplies. "It's a real headache to buy milk powder for my 18-month-old son," said Long, a resident of Huadu district, Guangzhou. "Before the new rule, a can of imported infant formula from Hong Kong was selling for between 200 and 250 yuan [HK$250-HK$312] in Huadu's shops selling Hong Kong products," she said. "Now the shops ask for up to 300 yuan per can. And the label price is usually meaningless - it's so hard to buy one even though you look across the city and would pay the 300 yuan." Long says taking the family on a shopping trip to Hong Kong would be exhausting, and she is considering weaning her son onto solid food. "We just shop for milk powder and we are not drug dealers," she said. "Why is it so insulting and prejudiced [in Hong Kong]? I regret having to wean my son so early." But the milk powder row is only the most visible sign of tension between post-handover Hong Kong and the nation of 1.3 billion people of which it is now part. In recent years, the heat of the debate on mainland-Hong Kong integration has been turned up, due in part to an influx of mainlanders giving birth, swamping tourist attractions, crowding public camp sites and snapping up goods and even properties in the city, which has sparked hostility from local residents. How to tackle the booming number of babies born to mainland parents became one of the hot issues in last year's chief executive poll. Leung proposed that public hospitals cease admissions of non-local expectant mothers from this year, and suggested the government stop allowing heavily pregnant women to cross the border to give birth in private hospitals. He lived up to his pledge, announcing the so-called zero-quota policy even before taking office. The number of babies born in Hong Kong to mainland parents has jumped over the past 13 years. In 2000, they accounted for 1.3 per cent of newborns in the city, but that figure had increased to about 30 per cent by the time measures were brought in to curb the trend. The boom strained local obstetrics services, making it difficult for Hong Kong mothers to book a place in hospitals, and led to worries over the long-term burden on the city's education, health and welfare services. Last year, 26,715 babies were locally born to mainland parents, a quarter fewer than in 2011. Leung's policy won applause from local mothers, but disappointed mainland parents - in particular those who sought to have a second child in Hong Kong to circumvent the mainland's one-child policy, and mainland mothers married to Hong Kong husbands. It was also a blow to local private hospitals, which had invested heavily in maternity services. The question of right of abode for babies born to mainland parents - who prize a Hong Kong identity card for their children - remains the subject of a high-profile court case. And tension has spilled over onto the streets. In January last year, a Dolce & Gabbana security guard allegedly prevented a local photographer from taking pictures of the shopfront of its store at Harbour City, Tsim Sha Tsui and said that only mainlanders were allowed to do so. The incident infuriated some Hongkongers after it was exposed in the media. Many saw it as discrimination, and hundreds of people rallied outside the shop to protest. Later that month, remarks by Peking University professor Kong Qingdong , who branded Hongkongers "running dogs for the British government" in an internet talk show stirred up another controversy. He was commenting on footage that appeared on the internet of MTR passengers berating a mainland family for allowing a child to eat in a train carriage, which is banned. While the academic later denied making the comment, some internet users reacted by labelling visitors from across the border "locusts", implying that they sap the city's resources. In March last year, a long-delayed plan to make it easier for mainland drivers to bring their cars to Hong Kong - and vice versa - hit setbacks after some Hongkongers raised concerns about more accidents, worse air quality and heavier road congestion. Many questioned whether more left-hand-drive vehicles should be allowed in. The first phase of the trial quota scheme, which allows Hong Kong private car owners to drive to Guangdong via the Hong Kong-Shenzhen Western Corridor once, for a stay of no more than seven days, began in late April. But there remains no timetable for the second phase, in which a certain number of mainland cars will be allowed into Hong Kong. Meanwhile, hot money from the mainland has flooded into the city's already inflated property market. The government last month doubled the sales tax on properties costing more than HK$2 million and targeted commercial real estate as the potential for a bubble spread from homes to parking spaces, shops and hotels. That followed the government's decision in October to impose an extra 15 per cent tax on all home purchases by companies and non-permanent residents, adding to earlier steps including tighten mortgage lending. In September, Leung announced that flats to be built on two plots at the former Kai Tak airport could only be owned by permanent residents for 30 years. Leung has also focused on increasing the supply of subsidised housing. While mainland-Hong Kong integration has been the aim of both governments, some measures Leung's administration has rolled out - from the milk-powder export limit to "Hong Kong properties for Hong Kong people" - have led observers to ask if he is driving the two sides further apart. Dr Chung Kim-wah, assistant professor in the Polytechnic University's department of applied social sciences, says Leung's approach is understandable. "Except where there are conflicts, Hong Kong should work for the nation's integration. But at a time of conflict, what he did was necessary," he said. "It might not be easily acceptable [to those affected] in the short run. But in the long run, it could ease bilateral conflicts. "Say there was no export restriction and the problem of parallel-goods traders snapping up milk powder worsened. The [anti-mainland] sentiment might further heat up." Chung added: "Irrespective of whether his moves are for pushing up his popularity, it is good to set out the rules in a timely way and prevent the problems from worsening." Leung, meanwhile, pledged to improve cross-border communication and seek a better understanding of the export rule. The government should "step up our communication measures to make sure that all, including residents on the mainland, understand the motives behind this, or the intent behind this piece of legislation, and also the content of legislation, so that there is no misunderstanding". Despite the influx of mainland travellers, Leung dodged questions about whether the multiple-permit entry scheme, which allows mainland visitors to make regular trips to Hong Kong, would be scrapped or otherwise limited. It could, perhaps, be another balancing act: an attempt to reconcile the vested interests of mainland travellers, local tourism-related businesses and Hongkongers. As for Long, even though it has become a pain to shop in Hong Kong, she says she will put up with it instead of feeding her mainland-made baby formula. "I trust and admire the Hong Kong government on food supervision. I appreciate it no matter how awful it is now for mainland shoppers."