Ms Braverman, 43, had been caught speeding last summer - and prior to paying a fine and accepting points on her licence, reports suggest the home secretary allegedly asked civil servants to arrange a private one-to-one speed awareness course for her.

The prime minister is under mounting pressure to order an inquiry into her conduct, and the issue is at the top of his agenda after arriving back from the G7 summit in Japan this morning.

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Downing Street has said Mr Sunak will consult his ethics adviser, Sir Laurie Magnus, and he is also expected to hold discussions with Ms Braverman and Cabinet Secretary Simon Case.

Deputy Labour leader Angela Rayner has demanded that he go one step further and launch an independent investigation - as he did over Nadhim Zawahi's tax affairs - "without delay".

In a written letter to the prime minister, she said he must "show some backbone".

Ms Rayner also questioned whether the home secretary "encouraged or asked civil servants, officials or special advisers to breach the civil service code by supporting her to further her own private interests" and whether the prime minister himself "knew about the alleged attempts by the home secretary to involve her civil servants".

"Rishi Sunak was too weak to deal with Suella Braverman the last time she broke the ministerial code, and his reluctance to order an investigation right away speaks volumes on how seriously he takes his promise to bring integrity to government," she said.

A spokesman for the home secretary said Ms Braverman "accepts that she was speeding last summer and regrets doing so".

"She took the three points and paid the fine last year," they added.

But The Sunday Times reported that instead of signing up for an in-person course with other motorists, or completing one online that would show her name and face to other participants, Ms Braverman allegedly asked civil servants to arrange a private one-to-one course.

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When the civil servants refused, she reportedly sought help from a political aide, who requested the private course organiser provided a private session, or allowed her to use an alias or turn her camera off.

When the provider refused, Ms Braverman opted to take the three points on her licence, the paper reported.

Earlier on Sunday, Mr Sunak refused to back the home secretary when asked about the row at the end of the G7 meeting by a reporter.

"I don't know the full details of what has happened, nor have I spoken to the home secretary," he said.

"I think you can see first-hand what I have been doing over the last day or so, but I understand that she's expressed regret for speeding, accepted the penalty and paid the fine."

However, a No 10 spokeswoman later insisted he does "of course" have full confidence in her.

Speaking on the Sky News Sophy Ridge On Sunday programme, Environment Secretary Therese Coffey said it was "perfectly normal" if people are given points for speeding, but maintained that she was unaware of all the details referred to in the newspaper.

Meanwhile, the incident was called "shocking" by Ms Braverman's opposite number, the shadow home secretary Yvette Cooper.

"We've had 13 years of the Tories trying to dodge the rules for themselves and their mates. Enough is enough," said Ms Cooper.