These moves, announced yesterday by the Permanent Secretary for Economic Development and Labour, Matthew Cheung Kin-chung, come amid a growing row over the unpaid wages of workers of government contractor Dickson Construction.

Mr Cheung said the government would consider increasing the penalty for contractors failing to comply with the new measures and a taskforce would be set up to study the sub-contracting system in the construction industry.

'The Dickson case is a good opportunity for us to have a closer look at the issue,' said Mr Cheung, who described the moves as a breakthrough in the protection of labour rights. But he said the new measures would not apply to contracts already awarded.

Unionists generally welcomed the measures but said they came too late. Construction Industry Employers General Union chairman Choi Chun-wa said: 'The measures are long overdue. But the government should not overlook the plight of those involved in the Dickson case.'

Earlier in the day, Mr Choi's union, along with the Federation of Trade Unions, led 500 workers on a march to the Central Government Offices to protest against the government's lax monitoring of its contractors.

Unionist legislator Wong Kwok-hing, who later led 30 representatives to protest outside Government House, said: 'The problem is not only in the construction industry. We also hear complaints from security guards and cleaning workers that they are not paid what they were promised.'

Mr Wong urged the government to review its tendering procedures and not to award contracts to bidders with suspiciously low offers.

'Low offers are often made possible by exploiting workers,' he said.

Mr Wong, who also supports the unpaid Dickson workers, said he was considering seeking a judicial review to press the government to pay the workers an ex gratia payment under the Protection of Wages on Insolvency Ordinance.

He said there was no excuse not to pay because court actions had been brought against Dickson Construction by its creditors.