Foreign Secretary David Miliband spoke to his Iranian counterpart last night and called for the speedy release of the five captured British sailors.
Mr Miliband pressed Iranian Foreign Minister Manouchehr Mottaki for information on what his country were planning to do with the yachtsmen.
A Foreign Office spokes-woman said: “He pressed Mr Mottaki for clear information on what had happened and for a statement of Iranian intentions in respect of the five.
“He reiterated our demand for formal consular access to the men and his hope that this issue be brought to a speedy conclusion and the release of all five.
“The Iranian Foreign Minister undertook to get the foreign secretary a response on these points at the earliest possible opportunity.”
Earlier the Iranian ambassador to the UK attended the Foreign Office to hold talks over the sailors as fears grew for their safety.
Rasoul Movahedian spent 30 minutes speaking to permanent under secretary Peter Ricketts following the crew’s capture last Wednesday.
The Kingdom Of Bahrain racing yacht, owned by Sail Bahrain, was stopped by the Iranian navy as she sailed from Bahrain to Dubai.
Oliver Smith, 31, from Southampton, Oliver Young, 21, from Saltash, near Plymouth, Sam Usher, 26, from Scarborough, North Yorkshire, Luke Porter, 21, from Weston-super-Mare, and Bahrain-based radio presenter David Bloomer, thought to be in his 60s, were on board.
Earlier Mr Miliband said there was “no confrontation or argument” in discussions with Iran and stressed the capture had “nothing to do with politics”.
But he said there was a “high level of concern” about the sailors, whose location is unknown.
Esfandiar Rahim-Mashaie, Iranian president Mahmoud Ahmadinejad’s head of staff, told the country’s Fars news agency: “Our measures will be hard and serious if we find out they had evil intentions.”
The families of the captured sailors will meet Foreign Office officials in London today.
Mr Porter’s mother, Beverly, of Weston-super-Mare, said her son did not have an “evil bone in his body” and stressed the vessel’s apparent diversion into Iranian waters would have been an innocent mistake.
Mr Young’s mother, Susan, of Saltash, said she was confident that her son would cope.
The crew was heading to Dubai to join the 360-mile Dubai-Muscat Offshore Sailing Race.