The UK's biggest rail union is to withdraw financial support for heavyweight Labour MPs including John Prescott and Robin Cook.

Bob Crow, general secretary of the Rail Maritime and Transport Union (RMT), said the union should sack the 13 MPs currently on its pay roll because Labour has failed to renationalise the railways.

The patience of many of our members and traditional Labour supporters is now wearing thin

Bob Crow RMT general secretary

The RMT agreed overwhelmingly to make a hefty cut in its financial contribution to Labour, from �110,000 down to �20,000 - the biggest proportionate reduction so far by any union.

Chancellor Gordon Brown on Wednesday insisted such action would not divert the government from pursuing the national economic interest.

"We will not make decisions for sectional interests or because one union says it wants this or that," Mr Brown told BBC Radio 4's Today programme.

On Tuesday, the RMT also gave approval to a measure that will scale down its affiliation level to the party from 56,000 members to just 10,000.

Favoured group

Speaking after delegates voted for the changes at the RMT conference in Southport, Mr Crow claimed Labour had betrayed working people.

Delegates voted to switch their allegiance to a fund available to 14 left-wing MPs, including Diane Abbott, Jeremy Corbyn, Ann Cryer and Brian Donohoe.

John Prescott has lost the union's backing

Mr Crow said these MPs could use the cash to campaign for renationalisation of the railways, against privatisation of London Underground, for the repeal of trade union legislation and in support of seafarers.

But Labour MP Tony Wright said he thought the union's move was "a digrace", adding that it went against the historic relationship between the party and unions based on "trust, loyalty and respect".

Deputy Prime Minister John Prescott and Commons leader Robin Cook were among a favoured group who had been supported through donations to their constituency parties.

Mr Crow said the proposal was not a "personality matter". It was about being represented by MPs that signed up to the union's aspirations.

"We are moving from a constituency group to a campaign group of MPs," he told BBC Radio 4's Today programme.

Replacement MPs

"We wrote to every single Labour MP ... and we have asked them, 'can you support the RMT charter' and as a result of that, people have either decided that they can support the RMT charter or not."

Ms Abbott, MP for Hackney North and Stoke Newington, told BBC News 24 she was pleased to be sponsored by the RMT, although she stressed the support was not about money.

"The point for me is that the policies that the RMT is campaigning for, which is to put British Rail back into public ownership, stop the privatisation of the tube, these are policies that are very popular in Hackney and these are policies I want to work with the RMT on," she said.

Not all the 14 MPs who backed the four RMT campaign issues are happy with the union's action, with two expressing reservations to BBC Radio 4's World at One.

'Serious mistake'

Mr Prescott, who is a member of the RMT, was aware of the switch of support to other Labour MPs.

Mr Crow said: "The patience of many of our members and traditional Labour supporters is now wearing thin but for the trade union movement to abandon the Labour Party would be a serious mistake.

"Labour was created as the political voice of the trade union movement and our members have the right to expect our political representatives to take up the cudgels on the issues that affect workers."

In March, the UK's main postal workers union, the Communication Workers Union, announced it was slashing its funding of the Labour Party by �500,000 over the next three years.

Its protest was over plans to axe about 15,000 staff.