Suella Braverman should quit if found to have breached the ministerial code by asking civil servants to arrange a private speed awareness course for her, Labour leader Sir Keir Starmer said.

The Prime Minister is expected to speak to the Home Secretary on Monday following suggestions her alleged request for help from officials to arrange a one-to-one course instead of taking penalty points breached the ministerial code.

Mr Sunak will also seek advice from his adviser on ministers’ interests, Sir Laurie Magnus, about how to proceed.

Sir Laurie cannot begin an investigation into a minister’s conduct without Mr Sunak, who returned from the G7 summit in Japan early on Monday, signing off an inquiry.

“The Prime Minister has always followed the proper process in these matters, and will consult the independent adviser upon his return to London,” a No 10 source said.

Mr Sunak is also expected to speak to Cabinet Secretary Simon Case following suggestions it was the Cabinet Office that ordered Home Office officials not to offer Mrs Braverman advice on securing a private course.

The Home Secretary will appear before MPs for a scheduled question time on Monday afternoon, where she could be challenged about her actions.

Labour leader Sir Keir said her actions appear to have been “inappropriate” and she should resign if she is found to have breached the ministerial code.

He told ITV’s Good Morning Britain: “I don’t know all the facts but it looks to me as though the Home Secretary’s actions were inappropriate and they should be investigated.”

Sir Keir said he did not want to get “ahead of himself” in calling for Mrs Braverman to resign but said: “I think if she’s breached the ministerial code she should go … in the end it’s the ministerial code that matters.”

Dave Penman, general secretary of the FDA union which represents senior officials, told Sky News: “Civil servants are publicly funded. They’re paid for by you and me. They’re not there to support the personal interests of a minister.

“They don’t do their shopping, they don’t look after their children and they don’t sort out their speeding fine.”

Former senior civil servant Philip Rycroft said: “This, on the face of it, I think, is a breach of the ministerial code.”

The former permanent secretary at the Brexit department told BBC Radio 4’s Westminster Hour programme: “The code is very clear. Ministers must ensure that no conflict arises or appears to arise between their public duties and their private interests.”

The row stems from a Sunday Times report that Mrs Braverman asked Home Office civil servants to help arrange a one-to-one driving awareness course, rather than the group session usually offered to motorists for minor speeding offences.

Officials are said to have refused the request, so Mrs Braverman allegedly turned to a political aide to assist her in attempting to arrange an alternative to a course with members of the public.

A spokesman for the Home Secretary said she regretted speeding and had since accepted the points and paid the fine.

The speeding offence reportedly took place on a road outside London last year when Mrs Braverman was serving as attorney general.

But The Sunday Times said it was not until she became Home Secretary during Liz Truss’s brief premiership that the senior Tory called on the Civil Service for advice.

According to The Daily Mirror, the Home Secretary’s special adviser repeatedly denied that Mrs Braverman had been caught speeding when a reporter from the newspaper put the suggestion to them last month.

The newspaper has published a transcript of the exchange. The aide declined to comment when approached by the PA news agency.

Allies of Mrs Braverman have claimed she is being targeted as part of a smear campaign against one of the leading voices on the Tory right.

Tory MP Miriam Cates told the Daily Mail: “Suella has done nothing wrong.

“Around 1.5 million people take speed awareness courses every year so it’s hardly a news story. In smearing the Home Secretary like this, someone is clearly seeking to play the man not the ball.

“It’s underhand and undermines democracy.”