In a groundbreaking decision that will now land the government back in the British courts and force it to change the law, ECJ judges have upheld the opinion of the Advocate General that the European Working Time Directive precludes national governments from excluding groups of workers from the rights that the directive gives them. The ECJ is expected to back that opinion.

The UK government excluded millions of employees from accruing their rights to paid annual leave under the Working Time regulations until they had completed a qualifying period of employment of 13 weeks with their employer.

Stephen Cavalier, head of employment rights at Thompsons, the leading UK law firm which took the case on behalf of Bectu - the broadcasting and entertainment union said he was delighted with the ruling. He called on the government to make immediate changes to the working time regulations.

"The ECJ has stated clearly that paid annual leave constitutes a social right directly conferred by the directive on every worker as the minimum requirement necessary to ensure protection of health and safety and that this is a particularly important principle of Community social law from which there can be no derogations."

The ruling warns that derogations "are liable to give rise to abuse" by employers and it states that the UK government took the decision to exclude this group of workers on purely economic considerations.

Roger Bolton, general secretary of Bectu, said: "We are particularly pleased that the ECJ has concluded that workers on short-term contracts often find themselves in a more precarious situation than those employed under longer-term contracts and that it is all the more important to ensure that their health and safety is protected."