Primrose Hill resident and former Haverstock School pupil David Miliband has announced he is leaving British politics and the UK to take up a job heading an international charity in New York.

The former foreign secretary, who has been long regarded as one of the brightest Labour stars of his generation, will be the new chief executive of humanitarian organisation, the International Rescue Committee.

Mr Miliband, 47, said it was very difficult for him to be leaving politics, and he still “passionately” wanted to see Labour returned to power. He praised younger brother Ed’s leadership for making it “achievable”.

Since losing to Ed in Labour’s 2010 leadership contest he had sat on the back benches but a series of high-profile interventions prompted speculation that he might take up Ed’s offer of a place on the front bench. That prospect has now been scotched.

Mr Miliband, the son of Jewish immigrants, said he had “an additional personal motivation” in taking the job for the IRC, which was founded at the suggestion of Albert Einstein in the 1930s for those fleeing the Nazis. I feel that in doing this job I will be repaying a personal debt.”

It is not known whether he will sell his home in the capital.