LONDON (Reuters) - Britain said on Tuesday it had withdrawn all staff from its embassy in Sanaa, Yemen's capital, and extended the closure of the mission until further notice.

"Due to increased security concerns, all staff in the British Embassy have been temporarily withdrawn and the Embassy will remain closed until staff are able to return," the Foreign Office said on its website.

"There is a very high threat of kidnap from armed tribes, criminals and terrorists. Be particularly vigilant during Ramadan, when tensions could be heightened," it said.

(Reporting By Mark Anderson; Editing by Pravin Char)