Berlin - German Chancellor Angela Merkel's Christian Democrats (CDU) have slumped to their lowest popularity rating in more than two-and-a-half years, according to an opinion poll published Wednesday.

The survey, conducted by the Forsa research institute for Stern magazine and RTL television, showed the CDU on
33 per cent, a drop of 1 per cent from a week ago.

The Social Democrats (SPD), which rule in a grand coalition with Merkel's conservatives, gained 1 per cent to stand at 24 per cent.

Germany votes in a general election on September 27 when the CDU hopes to win enough votes to ditch the SPD and form a new coalition with the business-oriented Free Democrats (FDP).

The Forsa poll showed the FDP on 17 per cent, enough for a majority with the CDU. The SPD's preferred partner, the Greens, were on 11 per cent, the same as the radical Left party.

The last time the CDU's popularity was so low was in July 2006.

In a separate Forsa survey, some 48 per cent said they would prefer Merkel as chancellor, against 25 per cent who favoured her SPD rival Frank-Walter Steinmeier, Germany's current foreign minister.

Some 2,500 people were polled in the party survey and 18,500 on the issue of who they would like to see as chancellor. The margin of error was 2.5 per cent. (dpa)