Energy minister Claire Perry faces being investigation for shouting and swearing at civil servants after trade unions complained about her bullying of staff.

Three unions have written a joint letter to Alex Chisholm, the permanent secretary at the Department for Business, Energy and Industrial Strategy (BEIS) about ministers' behaviour.

Ms Perry was singled out for criticism amid claims there have been a series of reports about her abuse of officials.

Energy minister Claire Perry (pictured in Downing Street last week) faces being investigation for shouting and swearing at civil servants after trade unions complained about her bullying of staff

While the letter does not spell out specific instances, the Guardian said it understood Ms Perry allegedly texted one official to say 'f*** off'.

On another she is accused of scrawling 'what's this s***' on a memo produced by staff.

Ms Perry was promoted to Energy Minister last year. The job involves attending Cabinet but she is not a member of the PM's top team.

Labour's shadow cabinet office minister Jon Trickett demanded an inquiry.

He said: 'The unions have raised serious allegations, and we've got to look into them carefully.

Labour's shadow cabinet office minister Jon Trickett (file image) demanded an inquiry

'All ministers, however important, must pay close attention to relations with their staff, and avoid any conduct that could be seen as unprofessional.

'Bullying is totally unacceptable in any workplace.'

The ministerial code insists members of the Government should behave in a way that is 'proper and appropriate' with officials.

It continues: 'Harassing, bullying or other inappropriate or discriminating behaviour wherever it takes place is not consistent with the ministerial code and will not be tolerated.'

A spokesman for BEIS said: 'Like all government departments we are committed to ensuring that our staff are treated with respect. We have clear codes of conduct in place, with high standards expected of all.

'Any complaints or grievances made by staff are investigated following agreed internal processes.'