Women at the top of the banking industry spur their male colleagues to take bigger risks, according to a study that undermines the widely held view of the calming influence female staff have on testosterone driven company boards.

The report claims that the presence of women in senior roles across the German banking sector was a contributing factor to the banking crash, alongside the bonus culture and lack of sufficient regulation.

In the study for the German central bank, the Bundesbank, the academics argue that less experienced bankers catapulted into senior roles also contributed to risky behaviour, along with directors who had not taken education far enough to gain a PhD.

While the banks under review were all in Germany, with a two tier board structure, the researchers said the findings could be applicable to countries with simpler single board structures like the UK and US and should be taken seriously by policymakers.

Women, they said, are a disruptive influence on previously cosy decision making of male boards. Without a homegeneous group at the top to discuss relevant issues in a relaxed atmosphere, decisions are less well informed and inherently riskier.

More importantly, according to the research, the women at the banks studied were less qualified than their male counterparts, partly because they were younger on average and had reached board level with less direct business experience.

The report accepts research that found women working in the loan departments of banks have a lower default rate than male staff, but say the reverse is true at senior levels, especially when they bring down the average age and levels of academic qualifications.

"One reason may be that managers without such degree may have to climb up the job ladder without the signalling advantage of a PhD degree. To reach top executive positions, they have to prove their ability by extraordinary performance which is likely to be related to higher risk taking," the report said.