Two democratic groups have proposed slapping an arrival tax of HK$20 to HK$100 on non-Hong Kong residents who enter the city by land as a means of curbing the influx of mainland visitors.
But the idea drew a hostile reaction from the tourist industry, which said it would damage the city's image, and a Beijing-friendly lawmaker who said it was a rather a "brutal" solution.
The biggest tax, HK$100, was suggested by radical group People Power. The Democratic Party proposed HK$20 to HK$50.
Concern about Hong Kong's ability to absorb mainland tourists has risen since commerce chief Greg So Kam-leung estimated last month that tourist numbers could climb 30 per cent to 70 million a year in three years, and to 100 million in a decade.
Watch: Can residential areas in New Territories handle mainland tourists?
"We are not trying to drive all tourists away, but to control - or stabilise - the numbers of tourists," Democratic Party lawmaker Sin Chung-kai said. "Hopefully the proposed tax would discourage mainland tourists - particularly parallel-goods traders - from travelling to Hong Kong."
The party said about 20 million or 88 per cent of the 23.1 million independent travellers in 2012 entered the city by land.
People Power lawmaker Albert Chan Wai-yip said his party's more aggressive plan might stem the influx of at least 10 million mainland travellers a year who enter and leave on the same day.
When asked about Chan's proposal, Secretary for Security Lai Tung-kwok said he would not comment on it but stressed his bureau was taking steps to ease the traffic load at borders. Future plans included more checkpoints and promoting the use of automated passenger clearance.
Watch: Can Hong Kong's border checkpoints handle more tourists?
Travel Industry Council executive director Joseph Tung Yao-chung said a charge would undermine Hong Kong's image.
"I haven't heard of any places in the world that charge an arrival tax," he said, adding that the government should figure out ways to cope with the flood of tourists instead of imposing a new tax.
Ocean Park chairman Allan Zeman said: "I'm worried that this would make visitors feel unwelcome. They can go to many places in Asia and do not have to come to Hong Kong."
Federation of Trades Unions lawmaker Wong Kwok-kin said an arrival tax was a "brutal" way of dealing with the problem.
"It gives people an impression that the measure is targeting a specific group of people - mainlanders - and it is discriminative."
In 2003 the then financial secretary, Antony Leung Kam-chung, proposed a land departure tax of HK$18, but it was scrapped in the face of widespread political opposition.