The EU's top court has ruled that companies may pay women less than their male colleagues if their length of service is shorter because of taking time off to look after children.

In a keenly awaited ruling, the European Court of Justice (ECJ) said employers did not have to justify on a case-by-case basis their pay structures based on the length of service, unless a worker provides evidence that raises serious doubts.

The Luxembourg-based court rejected a claim by British health inspector Bernadette Cadman who had said her employer unjustifiably paid her male colleagues of the same grade more only because they had worked more years.

Cadman had argued length of service often depended on domestic circumstances such as pregnancy and maternal leave and that employers must provide special justification for paying men more than women when they hold the same post.

'Recourse to the criterion of the length of service is appropriate to attain the legitimate objective of rewarding experience acquired which enables the worker to perform his duties better,' the court said in its ruling.

Cadman sued Britain's Health and Safety Executive in 2001 when she discovered she was earning up to £9,000 a year less than male workers in the same post. Britain's Employment Tribunal initially ruled in her favour but an appeals court had doubts and referred the case to the ECJ which interprets pan-EU legislation.

Cadman's lawyer has been quoted as saying the case was 'the most important equal pay claim to be brought in the last 10 years'.