British Prime Minister Boris Johnson is expected to resign today, with his office saying he will make a statement to the country.

"Boris Johnson will resign as Conservative Party leader today," BBC political editor Chris Mason said on Twitter.

Johnson had been hanging onto power despite the resignation of a string of his top ministers. Today, the man he appointed as finance minister less than 48 hours earlier publicly urged Johnson to quit.

"The prime minister will make a statement to the country today," a spokesperson said.

Defence secretary Ben Wallace also called on Johnson to quit but said he would stay in his role to protect national security.

The Sun political editor Harry Cole said Johnson was aiming to carry on as prime minister until a new leader was chosen later in the summer, a task that can take up to two months.

- Reuters