Tensions between UK and Russia soared over Syria-bound helicopters

Britain came alarmingly close to a dangerous clash with Moscow when David Cameron was asked to consider giving an order to forcibly board a ship headed towards the English Channel carrying three Russian-made helicopters for delivery to the regime in Syria, it emerged today.

Any seizure would have been carried out by members of the Special Boat Service, SBS, the only military unit authorised to performing opposed embarkations at sea. The helicopters are believed to be the same ones that prompted US Secretary of State, Hillary Clinton, recently to berate Russia for sending military hardware to Syria.

Officials traveling with the Prime Minister on an official visit to Mexico City yesterday gave the first detailed account of a series of high-level meetings that happened at Whitehall at the end of last week as the authorities tracked the ship, the MV Alead, which was steaming southwards through the North Sea after departing from Leningrad port.

Mr Cameron was briefed on a continuous basis, they said, on the results of a series of meetings of the emergency Cobra committee as the ship approached waters off Dover. Officials said that at that point "all options were on the table" about preventing the ship continuing its voyage towards Syria. They did not deny that those options might have included an armed boarding and seizure of the vessel, an action that surely would have elicited Russian ire.

As the Government consulted with Denmark and the Netherlands on options for stopping it, the ship abruptly turned around on Friday, they said. But by the end of the weekend it was in the Hebrides area and bound westwards apparently on a course to go around Scotland and then south again towards the Straits of Gibraltar.

The crisis only eased, it seems, when an international maritime insurance firm was persuaded to withdraw coverage of the ship and its cargo. At noon on Monday, the ship had turned eastwards again. Yesterday, it was reported to be back in the Baltic seemingly headed back to Russia.

The near-scrape on the seas was raised by Mr Cameron at a bilateral meeting with Russian President Vladimir Putin at the Los Cabos G20 summit yesterday, sources said. He directly challenged him about arming the Syrian regime. Mr Putin responded with the assertion that other countries had been arming opposition forces in Syria.

Britain is expected to push the European Union to redraft parts of its arms embargo on Syria to extend it into the area of insurance. The changes would mean that any company found to be selling coverage to vessels bearing arms to Syra would be in violation of the sanctions. They said it would be handled at a foreign ministers council meeting in Brussels next week.

Asked directly if plans were laid to seize the Alead the senior UK official said they had "considered all options". Officials believe the three helicopters were already owned by the Syrian regime but had been sent to Russia for servicing. Returning them to Syria would have increased the size of its helicopter fleet by 10 per cent. Some air defence weaponry was also thought to be on the Alead.