The Foreign Office says it is "actively investigating" reports that five UK yachtsmen held by Iran's Revolutionary Guard for a week have been freed.

The crew were said to have mistakenly strayed into Iran waters as they sailed from Bahrain to Dubai for a race.

Iranian radio said they had been freed at 0730 local time (0400 GMT). It is thought they were held on Siri island.

The news comes hours after UK Foreign Secretary David Miliband spoke by phone to his Iranian counterpart.

Iran's official IRNA news agency said the five had been freed after an interrogation by authorities established that their yacht had entered Iranian waters "by mistake".

A statement by Iran's Revolutionary Guard said: "After carrying out an investigation and interrogation of the five British sailors, it became clear that their illegal entry was a mistake.

"After obtaining necessary guarantees, it was decided to release them."

BBC correspondent Christian Fraser in Bahrain said he had spoken to Vanessa Bloomer, Mr Bloomer's wife, who said she had received no independent verification of the men's release.

David Bloomer's wife said she had received no verification of his release

A BBC correspondent added there was still a lot of uncertainty about what was going on.

The family of Mr Young also told the BBC that they had not heard anything officially but were keeping their fingers crossed.

The five were detained after the Revolutionary Guard stopped their Volvo 60 yacht, called The Kingdom of Bahrain, in the Gulf on 25 November.

Families of the five men had been due to meet with Foreign Office officials later.

The BBC's Jon Leyne in Tehran said the investigation had been "lightning-fast" by Iranian standards.

Full story: www.bbc.co.uk