Britain's ruling Labour party is faced with its worst electoral debacle in four decades as  the Conservatives and Liberal Democrats pushed it to the third place in the local council elections, prompting calls for a leadership change in the party.

With two-thirds of over 4,000 election results announced by 0630 GMT (1200 IST),  the Labour party had so far lost over 140 seats while the Conservatives had made significant gains, winning 45 local councils, a net gain of eight councils.

Projections of voting percentages suggest that the Conservative party had recieved  44 per cent of the votes, Liberal Democrats 25 per cent and Labour 24 per cent.

The full results would be announced later on Friday. The most keenly awaited result is that of the London [Images] mayor, where the incumbent and Labour candidate Ken Livingstone is facing a stiff challenge from the Conservative journalist-MP Boris Johnson.

Commentators believe Prime Minister Gordon Brown's goal was to beat last year's result of 27 per cent of the vote. Anything less than 27 per cent was expected to raise questions about when Brown will join Tony Blair [Images] in retirement.

The poor performance by Labour is similar to the drubbing received by the Conservative Prime Minister John Major in local council elections in 1995, two years before he lost power to Tony Blair.

Election expert John Curtice of Strathclyde University told the BBC: "It looks quite possible that by the time all the results are declared some time on Friday afternoon, Labour will have suffered at least 200 net losses."

Failure by the Conservative party to exceed 40 per cent of the vote will raise questions about Cameron's ability to capitalise on Labour woes and break through to new voters. Curtice added it looked like "a relatively good night for the Tories". He said it appeared to be a "bad night for the Lib Dems", while Labour could "look forward to at best doing much as they did in 2004 and 2007".

Labour had won the first by-election after Brown assumed office, when the party's Virendra Sharma won the Ealing Southall election in July 2007.