Tens of thousands of part-time workers wrongly excluded from their workplace pension schemes will share in millions of pounds of compensation as their employers belatedly agree to pay backdated benefits.

More than 60,000 people, mostly women, stand to gain from the move, which follows a ruling by the European Court of Justice in 2000, and another by the House of Lords last year.

European employment law states that men and women must receive equal value for equal work, and the European Court ruled that this meant part-time workers had the same right of access to pension schemes as their full-time colleagues.

The court rulings mean that anyone who worked part-time between 1976 and 1995, when part-timers began to be allowed to join their workplace pension schemes, might be able to backdate their pension rights to the moment they started work.

To make a claim, employees need to lodge an employment tribunal application. This can be done at any time by people who still work for the same employer.

However those who have left or retired must lodge their claim within six months or they may not able to join the pension scheme.

Some major employers have already begun the compensation process.

High-street bank HSBC announced in March that it would let eligible part-time employees join its occupational pension scheme.

HSBC and finance union Unifi negotiated a settlement for about 2,000 current and former part-time employees which goes further than the basic legal requirements.

The process will not be cheap for employers who discriminated against part-timers in the past.

HSBC has set aside an estimated �25m to meet the cost of the claim, Barclays could be hit to the tune of �100m for its 13,500 part-time staff, and other banks are expected to follow suit. In all, Unifi estimates that the compensation process could cost the finance industry as much as �132m.

It is not just banks, however, that will have to meet claims from part-time workers excluded from their employers' pension schemes.

Pensions experts believe that the eventual cost of reimbursing part timers' lost benefits will run into many hundreds of millions of pounds as organisations across industry and the public sector reach agreement on the terms under which part-timers are readmitted to their pension schemes.