The legislation is already in place under the new Safety, Health and Welfare at Work act introduced by the Minister for Enterprise, Trade and Employment, Micheal Martin, last September.

But because of an expected backlash from unions, who argue that drug-testing is an infringement of civil liberties, Martin has delayed its introduction until unions and employers agree watertight rules.

Unions want any tests to be limited to workers in highrisk occupations only.

The current list of such jobs includes pilots, cabin crew and seafarers as well as bus, train, truck and taxidrivers.

All construction workers will also be liable to be tested as will gardai, firefighters, soldiers and prison officers.

But because the new laws are designed to prevent workers under the influence of drugs endangering others in their care, the list also includes teachers, childminders, nurses and doctors.

Fifty thousand Irish workers are already tested for drugs every year, it emerged at an Employee Assistance Programme Institute seminar last week.

These are mainly preemployment tests demanded by US multi-national companies operating here.