'I sympathise with owners of small businesses during this difficult period, but I would never tolerate them repeatedly [breaking the law] after successive warnings,' he said.

'Why do some of them not cover the food time and again? It is intolerable for them not to cover up food from people passing in dusty streets.

'It is a very good way to achieve deterrence by publicly naming offenders.'

Team Clean's interim report, published last month, says the government will step up enforcement against food premises that breach hygiene-related legislation and tenancy conditions. Repeated breaches will lead to termination of licences or inclusion on a list of 'dirty premises' for publication.

A union spokesman, however, warned that the hygiene campaign could lead to exploitation of cleaning workers.

Chief executive of the Catering and Hotel Industries Employees' General Union Mandy Li Kim-man said restaurants would be anxious to avoid inclusion on an 'unclean' list, but most were facing a shortage of staff.

'Before the Team Clean campaign came out, they only cleaned their places as part of the daily routine. Now they have to double efforts to make sure nothing is wrong. This can lead to longer working hours and possible exploitation of cleaning workers,' Miss Li said.

The Food and Environmental Hygiene Department yesterday inspected 754 licensed restaurants, factory canteens, food factories and cooked meat shops, issuing warnings to 23, prosecuting 48 and seizing 140kg of uncovered food.

Manager of the Super Star Seafood Restaurant at Amoy Gardens, Chow Oi-po, said the new punishments would have a deterrent effect, but a hygiene points system - as well as the chance of redemption - must also be offered.

'With such a bad economic environment, we need to offer high-quality yet cheap food. This is already placing huge pressure on us,' Ms Chow said. 'Why can't the government establish a system similar to the one designed for public estates?'

She was referring to the system in which public housing tenants have points deducted for unhygienic behaviour before ultimately facing eviction.

Ms Chow added that second chances should be given to most caterers as they were short of staff and could overlook their duties at times.

Fernando Cheung Chiu-hung, applied social sciences lecturer at the Hong Kong Polytechnic University, said the deterrent effect only applied to well-known outlets.

'I think the less famous ones would not care about having their names published anyway because the masses would not know who they were,' Dr Cheung said.

'But what I am concerned about is that it will lead to more opposition voices [to the cleanup].'

He added that naming and shaming was a 'negative' way of tackling the issue, and fines would be much more effective.

Legislator Tommy Cheung Yu-yan, catering sector representative of the Liberal Party, also said that publicly listing unhygienic restaurants would be unfair to businesses.

The government has proposed increasing the fine for pet owners who do not clean up after their animals from $600 to $1,500, the same as for litterers. The legislative amendment would be gazetted on June 20 and would be implemented if Legco does not object.