The British government will not move its proposed amendment to delay a decision over whether Prime Minister Boris Johnson should be investigated over accusations he misled parliament about breaches of COVID-19 rules, parliament's speaker said.

The opposition Labour Party on Thursday will call a vote on whether he should be investigated for contempt of parliament by its Committee of Privileges, and the government had said it would introduce an amendment to delay that decision.

"If the motion is passed, the committee will not begin their substantive work until the police investigations are complete, so that they will have all of that evidence before them one way or the other," said Britain's main opposition Labour Party leader Keir Starmer.