The British Prime Minister, David Cameron has said, Iran would face serious consequences after hundreds of protesters stormed two British diplomatic compounds in Teheran.

Offices were smashed and flags torn down in the attacks which followed demonstrations against sanctions imposed on Iran over its nuclear programme.

Mr. Cameron described the incidents as outrageous and indefensible. British Foreign Secretary William Hague called it an extremely irresponsible action, amounting to a grave breach of Vienna convention.

He said, Britain would hold the Iranian Government responsible for its failure to take adequate measures to protect the British Embassy, as it was required to do.

The United States and the European Union also condemned the attacks.

The Iranian Foreign Ministry expressed regret for what it described as the unacceptable behaviour of a small group of protesters.

Iran’s Foreign Ministry has expressed regret over the ransacking of British embassy by protesters in Teheran on Tuesday.

It has said the protesters behaviour was unacceptable and it respects international agreements to protect diplomatic sites.