Round-the-clock passenger crossings at Lok Ma Chau would be unable to cope with rising overall demand, the government was warned yesterday. Critics said that while the introduction of round-the-clock crossings, announced by Chief Executive Tung Chee-hwa on Wednesday, was a step in the right direction, it was essential that 24-hour opening was extended to much busier Lowu. The calls came as officials on both sides of the border prepared for the extended opening at the Huanggang-Lok Ma Chau crossing, due by the Lunar New Year. Secretary for Security Regina Ip Lau Suk-yee said the Immigration and Customs and Excise departments could cope with round-the-clock passenger clearance at Lok Ma Chau by redeploying staff. A spokesman for the mainland authorities at Huanggang said they had not yet received instructions from the central government for 24-hour operations. But they had started to prepare for the introduction of the measure and would need more staff. Commissioner for Tourism Rebecca Lai Ko Wing-yee said she did not expect a substantial number of Hong Kong people to cross the border as a result of the extended opening at Lok Ma Chau. But Shenzhen estate agents welcomed the move, saying they expected more people to purchase property there. Pressure was building on the government yesterday to extend 24-hour opening to the Lowu crossing. Peter Wong Man-kwong, executive director of the Hong Kong Chinese General Chamber of Commerce, said round-the-clock passenger crossing at Lok Ma Chau could ease the pressure at Lowu. 'But 24-hour passenger clearance at Lok Ma Chau is no substitute for round-the-clock opening of the Lowu checkpoint which copes with the majority of cross-border passenger flow,' said Mr Wong, also a local delegate to the National People's Congress. The Lowu checkpoint, the world's busiest land crossing, coped with a passenger flow of nearly 71 million in the first nine months of this year compared with about 12 million using Lok Ma Chau in the same period. Priscilla Lau Pui-king, associate professor with the Polytechnic University's department of business studies, said round-the-clock opening at Lowu was essential to ease pressure on cross-border passenger flow. But the Kowloon-Canton Railway Corporation chairman Michael Tien Puk-sun said this month it was impossible to operate rail services connecting to the border 24 hours a day, seven days a week because maintenance work had to be carried out. The railway is the only means of transport to the Lowu crossing. Executive councillor Cheng Yiu-tong said the government should clear obstacles to cross-border integration. 'But it's not timely to open the Lowu crossing round-the-clock because operation of rail services after midnight will create noise pollution.'