Demonstrators outside the British embassy in the Iranian capital, Tehran, today threw firecrackers and rocks into the compound earlier.
A crowd of about 200 were demonstrating against what is claimed to have been the illegal entry into Iranian waters of 15 British navy personnel who were arrested nine days ago.
A spokeswoman for the British Foreign Office said no one was hurt at the embassy and there was no damage to the building.
Iran TV meanwhile says it is to air what it calls confessions by two British sailors saying they were detained inside Iranian waters.
Earlier, the British Foreign Office described as unhelpful a speech yesterday by the Iranian President, Mahmoud Ahmadinejad, in which he accused Britain of arrogance.
In a speech in the city of Andinmeshk, Mr Ahmadinejad said: 'The British occupier forces did trespass our waters. Our border guards detained them with skill and bravery.'
He continued: 'But arrogant powers, because of their arrogant and selfish spirit, are claiming otherwise.'
The US President, George Bush, last night referred to the 15 British sailors and marines being held by Iran as hostages.
Mr Bush said Iran's actions were inexcusable.
The British Foreign Secretary, Magaret Beckett, said she had contacted Iran to seek a peaceful resolution to the standoff, which is now entering its second week.
