Sales of hotel rooms as residential flats will cut the city's supply of accommodation and harm tourism, the Tourism Board has warned.
The comment came after property giant Cheung Kong started on Monday to sell rooms in its Apex Horizon suite hotel in Kwai Chung.
Buyers do not pay stamp duty on commercial property.
"The building of new hotels has yet to catch up with the increase in tourist numbers," board chairman James Tien Pei-chun said onTuesday.
"Selling existing hotel rooms would worsen the situation," he said.
The number of tourists who stay at least one night has risen by 30 per cent from 2007 to 2011, compared with a 22 per cent increase in the number of rooms.
The overall occupancy rate of hotels ranged between 85 and 89 per cent, except in 2009 following the financial crisis and the outbreak of the H1N1 virus, when the rate dropped to 78 per cent.
Tien, who is also a property developer and lawmaker, believed Cheung Kong would have examined the legal issues before deciding on the sale.
However, he expected lawmakers to raise doubts.
"The plot ratio of hotels is 15, while that of residential sites is nine," he said. He also noted that some uncertainties were yet to be resolved. "Who will continue to pay for the hotel licence or manage the unsold rooms?"
Kowloon East lawmaker Paul Tse Wai-chun, who formerly represented the tourism sector in the legislature, believed there could be an accommodation shortage if hotels sold their rooms.
Michael Li Hon-shing, executive director of the Federation of Hotel Owners, said there were enough hotel rooms.
"Except for maybe the Lunar New Year when hotels are more in demand, we have an abundant supply of rooms and it's not a problem," Li said.