Number of work days lost to strike action soars by a quarter to hit one million

Official figures showed 1.041million working days were disrupted by stoppages last year - an increase of 250,000 over 2006.

Some 96 per cent of those lost were in the public sector.

Strike: Teachers at more than 1,000 London schools staged a one-day walkout over pay in April this year

The figures came as Labour's leading union backers withdrew funding from a string of senior Labour MPs for failing to champion union-friendly policies.

The GMB said it would stop sending money to the offices of more than 30 MPs, including Government minister Meg Munn, vice-chairman of the Labour party Stephen Ladyman, and a host of ministerial aides. They will each lose up to £20,000 a year.

General secretary Paul Kenny said the union was no longer prepared to fund MPs who treated workers with 'contempt'.

Demanding changes to Government policies on taxation, public sector pay, executive bonuses and social housing, he also warned that the union could reduce the size of its annual affiliation to Labour, worth £1.2million a year.

'We cannot be immune to the fact that many of our members do not vote Labour,' Mr Kenny said. 'There is a great level of frustration about the Government's failure to deal with simple, day to day, bread and butter issues that affect workers.'

Workers at the Grangemouth oil refinery held a two-day strike over a pension dispute in April

Environment Minister Phil Woollas, speaking yesterday at the GMB's annual conference in Plymouth, praised Mr Kenny for increasing the union's membership and improving finances.

'Paul, come and run the Labour Party,' he said.

There is increasing concern over Labour's almost total reliance on trade union leaders for funding.

Gifts from individual supporters have all but dried up in the wake of the cash for peerages affair and the collapse in Labour's political standing.

In the first three months of this year, 92 per cent of donations to the national Labour Party came from the unions, up from 52 per cent in the same quarter last year.

Opposition MPs demanded to know what 'deals' were being been done with union leaders to to secure their financial backing. The unions were delighted when the Government agreed earlier this year to give agency workers a raft of new rights, despite concerns from business.

Yesterday firemen, prison officers, teachers, civil servants and other public sector workers joined a TUC rally in Westminster to press the Government for bigger pay rises.

The figures showed that one million working days were lost in the public sector last year, up from 656,200 in 2006.

There were 90 separate stoppages. Prison officers went on strike last August tube workers in September and train and postal workers in October.

David Frost, director general of the British Chambers of Commerce, said: 'Industrial disputes have a direct impact on a business's day-to- day running and the Government needs to work much harder to improve its current handling of industrial relations.'

Shadow Cabinet Office minister Francis Maude said: 'Mired in debt, the Labour Party is being held over a barrel by union barons. This is extremely unhealthy for democracy.'