Former UK Prime Minister Boris Johnson. [Associated Press]

Former British prime minister Boris Johnson is expected to contest in the Conservative Party leadership race to replace Liz Truss, the Times has reported.

Truss announced her resignation after only 45 days in office on Thursday, raising questions on who will best take over the Prime Minister's office.

"He's taking soundings but is said to believe it is a matter of national interest," Times Political Editor Steven Swinford said on Twitter.

In July this year, Johnson announced his resignation after some of the top government officials quit.

The resignations were inspired by his last scandal to engulf, which marked an end to three years in which he tried to fight his way through one ethical lapse after another.

"Them's the breaks," he said.

He is remembered for taking Britain out of the European Union and steering it through COVID-19 and the war in Ukraine.

Johnson stepped down immediately as Conservative Party leader but said he would remain as prime minister until the party chooses his successor.