Rishi Sunak sent lockdown party questionnaire by Met Police

Chancellor Rishi Sunak is reported to have attended a party in the Cabinet Room of Downing Street in June 2020

Chancellor Rishi Sunak has received a questionnaire from the Metropolitan Police as part of its inquiry into No 10 lockdown parties, Treasury sources have told the BBC.

Mr Sunak was one of more than 50 people sent the document by officers looking at potential lockdown breaches.

PM Boris Johnson has returned his questionnaire to the police.

The Met said the questionnaires will ask what happened and "must be answered truthfully".

The prime minister and his government have been dogged by reports of staff parties in Downing Street when Covid-19 restrictions were in force.

Several Conservative MPs have called for Mr Johnson to resign over the row, but others have said they would withhold their judgement until the police investigation had concluded.

Mr Sunak is reported to have been present at a surprise birthday party for Mr Johnson in No 10's Cabinet Room in June 2020.

At the time, social gatherings indoors were forbidden under Covid regulations imposed by the government.

• How many parties are police investigating?

• A timeline of the lockdown parties

• What Covid rules were broken?

Mr Sunak, who lives next door to the prime minister in Downing Street, was asked about the gathering in an interview with BBC political editor Laura Kuenssberg earlier this month.

He said he had been in the Cabinet Room "100, 200, God knows how many times" for Covid meetings during the pandemic, adding: "You're asking me about something that happened almost two years ago."

The Met investigation into 12 events held across government was launched in late January, after an internal inquiry led by civil servant Sue Gray passed information to the force.

She did not publish her full report due to the police investigation, but in her initial findings, Ms Gray criticised "failures of leadership" in No 10.

The Met said it would contact people "believed to have taken part in the events in question to get their accounts".

The force said it would send questionnaires that have "formal legal status and must be answered truthfully", and that needed to be responded to within seven days.

Mr Johnson has returned his questionnaire, but Downing Street has since said his answers would not be made public.

The police said a fine would be issued to anyone found to have breached Covid regulations, though a decision is not expected imminently.

While the prime minister has said he would tell the public if he received a fine, police are unlikely to identify anyone else if they have been given one.