The German left is benefiting from the unfolding tax investigation and the anti-business mood it has fanned, pollsters said on Friday ahead of an important regional election in Hamburg on Sunday

Manfred Güllner, director of the Forsa polling group, said the Social Democratic party (SPD) had improved its rating since the tax inquiry kicked off last week with a raid on the house of Klaus Zumwinkel, who later resigned as Deutsche Post’s chief executive. Mr Zumwinkel has not been charged.