Unions are pressing for wider enforcement of a European working time directive which has now come in to effect.

An extra three quarters of a million workers will benefit from the directive from Friday.

The working week for aviation ground staff, sea fishermen and some road transport workers is now restricted to 48 hours, with an eight-hour limit on night working.

However oil rig workers, who were expected to be included, are still the subject of a dispute between the government and trade unions over their entitlement to the four weeks' annual paid holiday also included under the directive.

At present, employees work 26 weeks offshore, with a further 26 weeks onshore as compensatory rest, which can be unpaid.

Unions are objecting to government plans for two weeks of the holiday entitlement to be taken from their time on land.

Even though the two weeks would be paid, the Amicus trade union argues they should come from the 26 weeks spent offshore.

Employment relations minister Gerry Sutcliffe has written to the union, which represents 7000 workers, requesting a compromise. But Amicus is considering whether to lodge a complaint with the European Commission.

A spokesman described the situation as "blancmange", warning that a number of North Sea health and safety representatives were prepared to resign over the matter.

However, the Institute of Directors warned of "chaos" in the sector if the union were to get its way.

"Oil rig workers are claiming they're entitled to four weeks' paid leave under the directive when they already get two weeks off a months," said a spokesman.

"It's going to throw their whole shift pattern into chaos and will mean companies taking on extra workers to cover their time off."

Other professions were also excluded from Friday's implementation of the directive.

Airborne personnel will not be covered until December of this year, while HGV drivers will have to wait until March 2005.

There is some flexibility in implementing the rules for junior doctors, who are not expected to benefit from the basic provisions until August next year, with the 48-hour working week phased in by the deadline of August 2009.

Even with the delay, the Conservatives predicted problems for the NHS.

"Britain will have more trouble than most coming to terms with the Working Time Directive," said shadow health secretary Dr Liam Fox.

"Countries across Europe will find applying the directive extremely difficult. But Britain will find it more difficult than most as we suffer from a smaller number of doctors and a target culture rigidly imposed by the Government.

"Yet again the UK will be subjected to a one size fits all euro policy which may have very serious consequences for the provision of services to British patients."

The IoD warned the additional costs of the directive could "blunt" the UK's competitiveness.

"Extending the working time directive is another blow and an extra regulation which blunts our competitiveness," said the business lobby.

"Piling extra burdens on companies is making it harder and harder for them to compete."The organisation, which represents 55,000 company directors, has called on the government and the European Union to allow businesses to negotiate their own terms and conditions with employees.