Britain on Friday joined France and Germany in voicing anger at the way the Iranian regime is responding to street protests across the republic, deepening the divide between the European Union and the US over how to respond to the crisis.

On a day that saw a diplomatic clash after Ayatollah Ali Khamenei, Iran’s supreme leader, lashed out at London, Gordon Brown, the UK prime minister, delivered a forthright attack on the actions of the Iranian authorities in trying to suppress demonstrations over the disputed election.