UK's Cameron: Iran embassy attacks 'outrageous'

British Prime Minister David Cameron labelled an attack by Iranian protesters on the British embassy in Tehran "outrageous and indefensible" and called on the Islamic republic to prosecute those responsible.

Echoing earlier comments from Foreign Secretary William Hague, Cameron also warned of "serious consequences" for Iran, adding that Britain would consider what measures it would take in the coming days.

"The attack on the British embassy in Tehran today was outrageous and indefensible. The failure of the Iranian government to defend British staff and property was a disgrace," Cameron said in a statement.

"The Iranian government must recognise that there will be serious consequences for failing to protect our staff. We will consider what these measures should be in the coming days."