Members of the Internal Security Forces ride on their vehicle in front of a poster of Syria's President Bashar al-Assad (L) and his father, former Syrian President Hafez al-Assad, in the Alawite Jabal Mohsen neighbourhood in Tripoli, northern Lebanon Nov 18, 2013. [Photo/Agencies]

AMSTERDAM/UNITED NATIONS - Syria's chemical weapons could be processed and destroyed out at sea, say sources familiar with discussions at the international body in charge of eliminating the toxic arsenal.

Four days after Albania rejected a US request that it host a weapons decommissioning plant, western diplomats and an official of the Organization for the Prohibition of Chemical Weapons (OPCW) at The Hague told Reuters the OPCW was studying whether it might carry out the work at sea, on a ship or offshore rig.

Confirming the discussion, the OPCW official stressed there had been no decision: "The only thing known at this time is that this is technically feasible," the official said on Tuesday.

While other states, notably Japan, have dealt with chemical weapons at sea, mounting such a large and complex operation afloat would be unprecedented, independent experts said.

But given the equally daunting challenge of neutralizing over 1,000 tonnes of material in the middle of a civil war, and the reluctance of governments like Albania to defy popular protests against hosting any facility, it is being considered.

"There are discussions about destroying it on a ship," one US official told Reuters.

Syrian President Bashar al-Assad agreed to join a global ban on chemical weapons after Washington threatened air strikes following a major sarin gas attack on rebel-held territory in August, for which the Damascus government blamed its enemies.

OPCW inspectors have checked Syria's declared 1,300 tonnes of sarin, mustard gas and other agents and the organization decided last week that most of the deadliest material should be shipped abroad by the end of the year and destroyed by mid-2014.

While battles for control of the highway from the capital to the Mediterranean port of Latakia have raised questions over the trucking of the chemicals to the coast, the Albanian refusal on Friday took negotiators by surprise, sources said, and prompted a radical shift in thinking to keep the plan on schedule.