The Prime Minister spoke out angrily after senior officers at RAF Wittering in Cambridgeshire ordered personnel to wear civilian dress when visiting nearby Peterborough.

The decision was sparked by incidents where insults were directed at some of the airmen and women.

But Mr Brown insisted that the armed forces should be proud of their work in the controversial Iraq and Afghanistan campaigns and called on the police to ensure they received "respect".

"All our armed forces should be able to, and encouraged to, wear their uniform in public and have the respect and gratitude of the British people for the huge commitment to public service they show," Mr Brown told reporters in Number 10.

"I encourage the local police to back up our armed forces so that not only can our armed forces wear their uniforms in public, but they should have the gratitude of the British public for the work they do."

A Ministry of Defence spokesman said the decision at RAF Wittering was a local one made by station commanders.

Defence Secretary Des Browne described the situation as a "great shame", adding: "We must defend our forces' right to wear their uniforms in public."

Tory leader David Cameron urged police to come down "extremely hard" on those who abused members of the armed forces in the streets.

"I think it's appalling that that happens. It shouldn't happen and service personnel should feel confident about wearing their uniforms in public," he said in a radio interview.