Alleged lockdown violations at the PM house are being investigated by UK police.

British police will investigate alleged lockdown breaches at Prime Minister Boris Johnson's Downing Street residence after receiving evidence from an internal government probe into a series of gatherings.

Johnson, who in 2019 won the biggest Conservative majority in more than 30 years, is fighting for his political survival after a stream of leaks revealed that his staff held parties during the toughest peacetime rules imposed in Britain.

New allegations emerged late on Monday that he broke the COVID-19 lockdown rules he imposed by attending a surprise birthday party in Downing Street when social gatherings indoors were banned.

This was added to a long list of alleged lockdown violations in Downing Street, including one 'bring your own booze' party that Johnson claims he went to assuming it was a work function. 

On Tuesday, London's Metropolitan Police Commissioner Cressida Dick announced that an investigation would be launched. 

"I can confirm that the Met (Metropolitan Police) is currently examining a number of events that occurred at Downing Street and Whitehall in the last two years in respect to potential COVID-19 laws violations," she said. 

The government's Cabinet Office said in a statement that its inquiry, led by senior official Sue Gray, was still ongoing, and that it was in communication with the Metropolitan Police. 

However, media sources suggested that her report's release could be postponed. It has been expected thus week

After charges that he and his staff partied in the heart of the British state during the deadliest pandemic in a century, Johnson is now attempting to shore up his premiership. 

Boozy staff parties, suitcases of supermarket wine, a damaged children's swing, a wine fridge, and jokes by workers about how to present such events to media have all been reported throughout Britain's several coronavirus lockdowns. 

Johnson's approval ratings have plummeted as a result of the scandal, and his Conservative Party has fallen significantly behind the opposition Labour Party in opinion polls, raising the possibility of a leadership challenge from within his own party. 

Several Conservatives have called for his resignation, but fewer than the 54 needed to force a confidence vote among parliamentarians, which, if defeated, would result in his resignation.