Angela Merkel's main challenger in next year's German elections has claimed that the chancellor has an advantage over him because she is a woman.

Peer Steinbrueck of the Social Democratic party (SPD) told the Sunday newspaper Frankfurter Allgemeine Sonntagszeitung that Merkel had a "women's bonus" that counted in her favour.

He suggested female voters appreciated that the two-time chancellor was able to get her way within her party and in Europe.

In the same interview, Steinbrueck said German chancellors weren't paid well enough. Merkel currently earns about €18,000 (£14,800) a month.

Steinbrueck recently revealed that since leaving government in 2009 he has earned about €1.25m from speaking engagements on top of his salary as an MP.

"A German chancellor does not earn enough based on the performance that is required of her or him compared with the jobs of others who have far less responsibility and far more pay," he told the newspaper.

"Nearly every savings bank director in North Rhine-Westphalia earns more than the chancellor does," he said, speaking of his home state.

Steinbrueck said austerity measures being imposed on struggling euro zone countries were too severe and that there would be massive protests in Germany if a heavy dose of austerity were imposed so quickly.

"The savings measures are too severe, they're leading to depression," he said . "Some societies are being forced to their knees. Budget consolidation is in some ways like medicine. The right amount can save lives while too much can be lethal."