The British marine insurer Standard Club said it had withdrawn cover from all the ships owned by Femco, a Russian cargo line, including the MV Alaed.
"We were made aware of the allegations that the Alaed was carrying munitions destined for
Syria," the company said in a statement. "We have already informed the ship owner that their insurance cover ceased automatically in view of the nature of the voyage."
British security officials confirmed they had told Standard Club that providing insurance to the shipment was likely to be a breach of European Union sanctions against the Syrian regime.
They said they were continuing to monitor the ship, which has been the subject of a fierce international row since US Secretary of State Hillary Clinton last week revealed it was adding to the arsenal of weaponry available for Mr Assad to use against rebellious Syrian towns.
"We have various ways of keeping track of this ship and that is what we are doing," a source told The Daily Telegraph.
