Trade unions have written to the top official in the business department to raise concerns about claims that the energy minister, Claire Perry, has sworn and screamed at civil servants, the Guardian understands.

Representatives of three unions representing Whitehall officials wrote a joint letter to Alex Chisholm, permanent secretary at the Department of Business, Energy and Industrial Strategy (BEIS), citing wider concerns about the behaviour of its ministers.

The letter, from the PCS, FDA and Prospect unions, said the claims had been raised by BEIS staff, but that the unions could not detail specific instances owing to concerns that individuals involved could be identified.

They singled out the alleged behaviour of Perry, claiming there had been a series of reports about her alleged behaviour towards her civil servants.

It is understood that the complaints given to the unions include claims that Perry screamed and shouted, texted one civil servant to say “Fuck off”, and wrote, “What’s this shit?” on a memo produced by staff. The MP for Devizes became energy minister in June last year, a role that involves attending cabinet.

The letter, sent earlier this month, has not been made public, and the unions involved have declined to comment.

Jon Trickett, the shadow Cabinet Office minister, urged the department to act on the letter. “The unions have raised serious allegations, and we’ve got to look into them carefully,” he said.

“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.”

In January, the government updated the official code for ministerial conduct, featuring an expanded section on bullying and harassment.

The code says ministers’ working relationships with civil servants and others “should be proper and appropriate”.

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.”

BEIS had no specific response to the claims raised but noted that the results of staff surveys showed it was among the best-performing Whitehall departments for the fair treatment of staff.