With seven weeks to go until German elections, a billboard of Chancellor Angela Merkel sporting a very revealing low-cut dress has pepped up a campaign that has so far struggled to grab public attention.

The advertising campaign is by Vera Lengsfeld, a member of Ms Merkel's own conservative CDU party, who is running in a long-shot race in a left-wing district of Berlin for a seat in Parliament in the September 27 poll.

It shows a photograph of each woman in an evening dress showing plenty of cleavage with the slogan: "We have more to offer" emblazoned over the Chancellor's breasts.

Ms Lengsfeld, a 57-year-old former East German dissident, said she had not cleared the picture beforehand with the 55-year-old Merkel but told rolling news channel N24: "The CDU is totally relaxed about this."

"I find it amazing how little humour some people have shown over this placard. People are always complaining that election posters are boring and then as soon as someone does something different, people get annoyed," she said. Ms Lengsfeld said she had 17,000 visitors on her election blog since she shot into the public eye and added: "If only a tenth of them also look at the content of my policies, then I will have reached many more people than I could have done with a classic street campaign."

Ms Lengsfeld will have her work cut out, however, to turn the limelight into an election win.

Although the CDU party is flying high in the polls, she is running against a popular Green party veteran who won the constituency, Berlin's Friedrichshain-Kreuzberg district, with 43 per cent of the vote at the last election in 2005.