British media on Thursday said Prime Minister Boris Johnson has agreed to resign, ending an unprecedented political crisis over his future.

Johnson had rebuffed calls by his Cabinet to step down in the wake of ethics scandals. He gave in after more than 40 ministers quit his government and told him to go.

It was not immediately clear on Thursday whether Johnson would stay in office while the Conservative Party chooses a new leader, who will replace him as prime minister.

Earlier, British treasury chief Nadhim Zahawi called on Prime Minister Boris Johnson to resign, just 36 hours after Johnson put him in the job, while another newly appointed Cabinet minister quit her post.

Zahawi said Johnson knew “the right thing to do” was to “go now”. His predecessor, Rishi Sunak, resigned saying he could no longer support Johnson after a series of ethics scandals.

Education Secretary Michelle Donelan, who was appointed on Tuesday following the resignation of her predecessor, announced her resignation on Thursday morning.

Johnson has rejected clamours for his resignation, digging in his heels even as dozens of officials quit and previously loyal allies urged him to go after yet another scandal engulfed his leadership.

A group of Johnson’s most trusted Cabinet ministers visited him at his office in Downing Street on Wednesday, telling him to stand down after losing the trust of his party. But Johnson instead opted to fight for his political career and fired one of the Cabinet officials, Michael Gove, British media reported.

As of early Thursday, five Cabinet ministers had quit, including on Thursday Donelan and Northern Ireland Secretary Brandon Lewis who told Johnson in his resignation letter that "we are ... past the point of no return. I cannot sacrifice my personal integrity to defend things as they stand now.”

Some 40 junior government officials have also left amid a furor over Johnson's handling of sexual misconduct allegations against a senior official that was the latest in a long line of issues that have made Conservative lawmakers uncomfortable. (AP)