Sir Keir Starmer has announced that he will step down as the MP for Holborn and St Pancras, triggering a by-election in the London constituency.
In a statement to the Camden New Journal newspaper, Sir Keir said it had been a "huge honour and privilege" to represent the constituency for 11 years, but that he would now turn his focus to "international affairs".
Sir Keir, who stood down as prime minister earlier in the summer, said he was ready to "pass the baton to a successor".
In his statement released on Tuesday, he said: "I will now focus on other things and that will be international affairs including defence, security, trade and technology in a fast-changing world."
He added that he would continue working to combat violence against women and girls.
"I will also continue, as I have done for a long time now with others, to work on combating violence against women and girls; that is an issue that matters to me hugely," he said.
The announcement follows weeks of speculation about whether Sir Keir would remain as an MP following his resignation.
In a BBC interview shortly after stepping down as prime minister, Sir Keir said he would stay on as an MP until the next general election.
Sir Keir had represented Holborn and St Pancras for 11 years before announcing his decision to leave the seat.
