ROME (Reuters) - The removal and destruction of the most dangerous agents in Syria's chemical arsenal will likely be delayed because of security and logistical problems, but the final deadline of the end of June for eliminating all chemicals remains, the head of the world's chemical weapons watchdog said on Thursday.
The goal for eradicating mustard gas and principal chemical components for making Sarin and VX - known as "priority A" chemicals - was originally the end of March.
Syria has already missed a December 31 goal to transport the most toxic substances to a port and so far has loaded only a relatively small amount of chemicals - around 5 percent, according to a senior Western diplomat in New York - onto the Danish cargo ship Ark Futura.
Ahmet Uzumcu, head of the Organisation for the Prohibition of Chemical Weapons (OPCW), said he was "confident" that all the chemicals could be destroyed by the end of June - the original deadline for the complete elimination of Syria's chemical weapons programme and associated agents.
When asked whether the March 31 destruction deadline for the priority chemicals would be met, Uzumcu said: "As we were not able to meet the timeline for the 31st of December ... from my point of view what is important is really the end of June 2014, so we will do our best to meet it."
The OPCW later released a statement saying Uzumcu had confirmed while speaking in Rome that he "remains confident the deadline of 30 June 2014 for destroying Syria's entire arsenal of chemical weapons can be met."
The OPCW is overseeing the destruction of the Syrian arsenal as part of an international accord brokered by Russia and the United States after poison gas attacks on the outskirts of Damascus killed hundreds, including children, in August.
Chemical weapons were likely used in five out of seven attacks investigated by U.N. experts in Syria, where a near three-year year civil war has killed more than 100,000 people.
The Syrian government and the opposition have accused each other of using chemical weapons, and both have denied it.
Once the Danish ship has loaded all the primary agents, it will take them to the port of Gioia Tauro in southern Italy, where they will be transferred to a U.S. ship and later destroyed at sea.
Transporting the chemicals through a civil war is "quite challenging," Uzumcu said, renewing an appeal to groups that oppose Syrian President Bashar al Assad's rule to cooperate.
"The biggest area of concern is clearly the safe transportation of those weapons, chemical substances, from the sites in Syria to the port of Latakia," he said.
Syrian authorities say opposition groups attacked two chemical storage sites more than a week ago, Uzumcu said, adding this had not been independently verified and there was "no evidence" that chemical agents had fallen into the hands of rebel groups.
Uzumcu said he met a Syrian delegation on Wednesday at The Hague to try to address security concerns.
"Some additional measures are being taken right now to reduce risks. We hope that we can move relatively quickly in the coming weeks," he said.
Uzumcu is in Italy to address parliament about the transfer of the primary agents.
The U.S. ship MV Cape Ray, which has been specially equipped to destroy the nerve agents, is likely to be in the Mediterranean Sea by the end of January, Uzumcu said. The chemical transfer should take no more than 48 hours, he added.
As the international coordination to rid Syria of its arsenal continues, two sources familiar with the matter told Reuters on Thursday that Britain would award a contract to destroy around 150 tonnes of chemicals to French firm Veolia Environnement.
The chemicals will be processed at the firm's incineration plant at Ellesmere Port in Cheshire, England, the sources said.
(Additional reporting by Benjamin Mallet in Paris, Andrew Osborn in London, Eleanor Biles and Anotnella Cinelli in Rome, and Louis Charbonneau in New York,; Editing by Alison Williams and Cynthia Osterman)