A Russian-operated ship said to be carrying military helicopters to Syria appears to have turned back after its British insurer removed coverage for the vessel, U.K. officials say.

Britain's Foreign Office said Tuesday the ship, the MV Alaed, changed course in Europe after news reports emerged about its alleged contents. Earlier, the Foreign Office confirmed it was aware that a ship carrying a consignment of refurbished Russian-made attack helicopters was heading to Syria.

The ship has "turned back now apparently toward Russia," Foreign Secretary William Hague told British lawmakers in Parliament. The vessel appeared to have been avoiding U.K. territorial waters and EU territorial waters, his ministry added.

'We are working closely with international partners to ensure that we are doing all we can to stop the Syrian regime's ability to slaughter civilians ...'—Britain's Foreign Office

"It is good news that the shipment of attack helicopters we've been tracking in the North Sea in recent days is heading away from Syria," British Prime Minister David Cameron said during the G-20 summit in Mexico on Tuesday. "But we will continue to work to stem the flow of weapons."

The news came after the U.K.-based insurer Standard Club said it removed insurance coverage for the ship owner when it became aware it was carrying munitions, a clear breach of its rules.

Russian officials have not commented on the ship or its reported contents. The vessel's Russian operator, Femco, refused to comment Tuesday.

Russian President Vladimir Putin said at the G20 summit that only the Syrian people have the right to decide whether their president, Bashar Assad, steps down.

Putin said Tuesday that not all Syrians want a change in leadership and that all parties need to negotiate a solution to end the bloodshed.

U.S. President Barack Obama also addressed the violence in Syria, while speaking at the G20. He described his meetings with the leaders of Russia and China, two countries that have stymied U.S. efforts to take action against Syria at the United Nations, as productive but said they were "not aligned" with the U.S.

"I don't think it would be fair to say that the Russian and the Chinese are signed on at this point," Obama said. "But I do think they recognize the grave dangers of all-out civil war."

Britain has joined the U.S. and other countries in pressing Russia to halt arms shipments to Assad's regime. Opposition groups say more than 14,000 people have been killed since the Syrian uprising began in March 2011 with mostly peaceful protests. A ferocious government crackdown, however, led many to take up arms and the conflict is now an armed insurgency.

Syria is Russia's last remaining ally in the Middle East, and has been a major customer of Soviet and Russian weapons industries for the last four decades, acquiring billions of dollars' worth of combat jets, helicopters, missiles, armoured vehicles and other military gear. Russia has also shielded Assad's regime from international sanctions over its violent crackdown.

The Foreign Office said Hague has told Russian Foreign Minister Sergey Lavrov that all defence shipments to Syria must stop.

"We are working closely with international partners to ensure that we are doing all we can to stop the Syrian regime's ability to slaughter civilians being reinforced through assistance from other countries," the Foreign Office said in a statement.

The BBC reported Tuesday that the ship was about 80 kilometres off the Outer Hebrides off the northwest coast of Scotland. The Foreign Office said it was heading toward the Netherlands when it changed course to avoid Dutch territorial waters and turned north.

U.S. Secretary of State Hillary Rodham Clinton issued a harsh reprimand to Russia last week, saying that Moscow "dramatically" escalated the crisis in Syria by sending attack helicopters there. The State Department acknowledged later the helicopters she accused Moscow of sending were actually refurbished ones already owned by the Assad regime, but Russia was clearly annoyed, and the spat further fuelled tensions between the two countries over Syria.

It was not immediately clear whether the helicopters reported to be aboard the Alaed were the ones Clinton had been referring to.