Hong Kong will discuss with Shenzhen how to control the influx in visitors with administrative measures, according to a source.
From next month, changes in permit rules will allow 4.1 million non-permanent residents of Shenzhen to make multiple visits to Hong Kong.
This has sparked demands from Hong Kong to postpone the change, with critics saying it will overwhelm infrastructure.
The source did not elaborate on the measures to be discussed, but tourism veterans said a lesson could be learnt from 2009.
That was when Shenzhen launched a programme allowing people with hukou, or resident permits, to apply for multi-entry permits. Initially only executives from selected enterprises were eligible to apply, before the scheme was gradually expanded.
Despite Hong Kong's desire for discussions, Shenzhen's public security bureau said yesterday that it would stick to the original schedule and implement changes next month.
So far the Shenzhen security bureau does not plan to increase the number of people dealing with the permits or set quotas. But a spokesman said it would make adjustments as needed.
Beijing, Tianjin , Shanghai, Chongqing and Guangzhou will also relax rules on non-permanent residents, allowing them to apply for single-entry permits to Hong Kong.
Green Sense has pressed the government to estimate the number of eligible visitors, saying it could reach 20 million.
Hong Kong immigration officers will meet their bosses today to voice concerns about extra work due to the likely influx.
Meanwhile, academics and groups said the government should determine the city's maximum capacity for visitors and step up prosecution of those engaged in the parallel import trade. Parallel import traders buy goods in Hong Kong and resell them on the mainland.
Hong Kong had 16.6 million visitors in 2002, before the Individual Visit Scheme. Last year the number was 41.9 million, with 67 per cent from the mainland.
Professor Michael DeGolyer, of Baptist University's Department of Government and International Studies, said cramming too many people into busy districts could bring safety concerns.
While the capacity of Chek Lap Kok airport and ports had been considered, he said: "I'm just not aware that the government bothered to do an assessment on streets."
Professor Terence Chong Tai-leung, of Chinese University's Department of Economics, said the government may consider charging consumption or land departure taxes on visitors to curb their numbers.
The two also suggested building shopping malls near the border to cater for tourists, a planning tactic that is common in Canada and the United States.
Amid worries that visitors could join in parallel import trading, Sheung Shui district councillors want more prosecutions.