Mr Schroeder's popularity has waned since September's elections

Official results show the SPD took over 40 % of the vote, well ahead of its main rival and in contrast to dismal poll ratings nationally.

The result comes as a strong boost to Chancellor Schroeder as he seeks to push through controversial economic and social reforms.

The SPD has had a rocky ride since it won a narrow victory in last year's general election, and only three months ago it suffered damaging defeats in other state elections.

But the BBC's Ray Furlong says it is not clear whether the Bremen result will mark a reversal of that trend.

In national opinion polls the party remains deeply unpopular, and this latest election was fought on local rather than national issues.

Not invited

Our correspondent says the government is widely seen as having broken a series of promises, and there is widespread dissatisfaction over its handling of the economy, which is on the brink of recession, and over unemployment, which continues to rise.

Mr Schroeder's attempts to revive the moribund economy with a reform package which includes trimming back state benefits and making it easier to fire people, has sparked dissent within his own party and serious opposition from the unions.

They have accused him of betraying Social Democrat principles and dismantling the welfare state.

Mr Schroeder was apparently not invited to help out with campaigning in the Bremen poll in what is seen as a mark of his current unpopularity.

Next weekend a special SPD congress will vote on controversial economic reform proposals opposed by the left.