A legal bid by union activists to overturn a Labour Party ruling banning them voting in the party's selection process for London mayor has failed.

The ruling at the High Court in London will come as a blow to Labour left-winger Ken Livingstone, who was the candidate most likely to receive the Manufacturing Science and Finance union's backing had it been able to vote.

Reacting to the decision, Mr Livingstone called on the party to think again about denying individual members a vote in the mayoral ballot.

The six London MSF members brought the case after accusing Labour of acting unlawfully in barring the union as a whole from taking part in the electoral college.

The party banned the MSF from the ballot for failing to pay subscription on time.

But the activists said that the organisation was being treated unfairly because individual party members would still be allowed to vote providing they got their subscriptions in before the ballot.

"At the time that the subscriptions were due, we were being told that the unions were not going to be allowed to vote," said Mr Livingstone.

"The reality within the Labour Party is that payments are often late.

"So long as individual members pay up in time they will be allowed to vote," he said. "I don't see why there should be one rule for them and another for the unions.

Other trade unions including the Rail Maritime and Transport union and the train drivers' union Aslef, have also found themselves unable to take part in the vote.

Last week London members of the Transport and General Workers' Union, which is taking part in the selection contest, voted for Mr Livingstone by a massive 85.8%.

His nearest rival, Glenda Jackson, won 7.3% while Frank Dobson, Prime Minister Tony Blair's preferred choice, came in last with a humiliating 6.9%.

'Denied rights'

Speaking on Thursday, Laura Cox QC, for the six MSF members, told Mr Justice Jonathan Parker that her clients were being denied their rights "unlawfully".

But for the Labour Party, Gavin Millar said that the union members' case was "misconceived".

Labour's executive committee, he said, had quite properly decided last year to enfranchise only those organisations which were paid-up.