The shooting, which caused no injuries, came after Iran confirmed that it had recalled its ambassador from London for consultations following Britain's arrest of a former Iranian diplomat.

The embassy was closed late yesterday morning "until further notice" after being hit by gunfire, according to an embassy spokesman.

In London, a Foreign Office spokesman confirmed the shooting. "The bullets hit offices on the first and second floors of the building," he said. Three bullet holes could be seen in the reinforced windows on the second floor.

Witnesses quoted by the official IRNA news agency said the shots were fired from two motorcycles.

Following the incident, some 20 Iranian police officers were deployed in front of the building.

The Foreign Office said earlier Wednesday that Iranian ambassador Morteza Sarmadi had returned to his country amid worsening diplomatic relations between the two countries, but added: "This is not a downgrading of relations."

Iranian foreign ministry spokesman Hamid-Reza Asefi said: "Sarmadi is here for some consultations" without specifying how long he would remain in Iran.

British authorities arrested former Iranian ambassador to Argentina Hadi Soleimanpour on August 22 after an extradition request from Buenos Aires. He is accused of taking part in a 1994 bombing of a Jewish centre there that killed 85 people.

A diplomat in London, quoted by The Guardian newspaper, said Sarmadi had officially returned for consultations following a hastily arranged meeting with British Foreign Secretary Jack Straw on Monday.

The source said Sarmadi "may not return" after failing to win any compromise from Straw over the detention of Soleimanpour, who was ordered by a British judge on Friday to remain in custody until a court appearance on September 19.

Iranian Deputy Foreign Minister Ali Ahani, who flew to London to discuss Soleimanpour's arrest with Straw last week, on Tuesday summoned the British ambassador to Tehran, Richard Dalton, and criticized the British judge and prosecution, IRNA reported.