Her decision is an apparent blow to Labour's efforts to promote the image of "Cool Britannia" abroad.

The 26-year-old daughter of former Beatle Paul McCartney said she was leaving the post on Panel 2000, just three months after being appointed because of work commitments.

But according to the press reports, the real reason may be that she is angry that the government is trying to cash in on her trendy name and image.

Stella McCartney's participation on the committee was also announced before she had formally accepted and she was conspicuous by her absence at recent meetings.

The Foreign Office said it was "disappointed" her decision and said she would not be replaced.

Her appointment was announced shortly before her mother, Linda, died from breast cancer in April.

Panel 2000 was set up in April with the aim of suggesting ideas to promote Britain's modern image overseas.

Its members include Channel 4 presenter Zeinab Badawi, Lord Ali of Planet 24, ex-BA Chairman Sir Colin Marshall, former Gladiator Judy Simpson, Martin Bell MP and Peter Mandelson.