Mr Schroeder (right) wants a distinctive SPD election platform

Chancellor Gerhard Schroeder, stung by a defeat for his SPD in the key state of North Rhine-Westphalia, has shunned any joint platform with the Greens.

In an election "everyone tries to win the most votes possible against every other opponent," he told Die Zeit.

His words in the newspaper interview were echoed by other SPD leaders.

SPD Vice-Chairman Kurt Beck said "it won't be a question of Red-Green, but of the SPD".

And the SPD's Saarland chief Heiko Maas said the SPD must "have a very independent profile in this short campaign".

Bitter blow to SPD

The SPD has shared power with the Greens since 1998.

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Mr Schroeder plans to hold a confidence vote in parliament by 1 July - the first step in forcing an early general election.

If his government loses the vote, parliament will be dissolved and elections held by mid-September.

Mr Schroeder said the SPD's drive to be distinctive in the general election was "not a rejection of the constellation [with the Greens] in which we have worked so successfully together".

The SPD had governed North Rhine-Westphalia for 39 years before its defeat by the conservative Christian Democrats (CDU).

Commenting on the impending election campaign, Mr Schroeder told Die Zeit he would like a "very personalised debate, based on the two main candidates".