By Thomas Escritt and Fredrik Dahl
THE HAGUE, March 24 (Reuters) - The head of the organisation overseeing the destruction of Syria's chemical weapons stockpile said he still hoped Damascus could meet a final deadline of June 30 but it might miss that target.
Syrian President Bashar al-Assad's government agreed to destroy its chemical weapons arsenal by mid-year as part of a U.S.-Russian agreement negotiated after a chemical attack last August that killed hundreds of people around Damascus.
It has handed over roughly half of its stockpile to a joint mission with the United Nations but is several weeks behind schedule, blaming security problems for the delays.
"I think that some targets have not been met, but the deadline of 30 June still remains our target, and we think we can finish the destruction by that time, or close to that time," Ahmet Uzumcu, head of the Organisation for the Prohibition of Chemical Weapons, said.
An official at the OPCW, which won the Nobel Peace Prize last year, said Uzumcu meant the process could run past the June 30 deadline Damascus had agreed to. This was the first official indication it might not be met.
Experts have said the deadline is overly ambitious but Russia and the United States have invested huge resources and political capital in the operation, which is expected to cost hundreds of millions of dollars.
Uzumcu made the comments after meeting U.S. Secretary of State John Kerry, who is in the Netherlands with President Barack Obama for a G7 meeting leaders on the crisis in Ukraine.
Kerry said he hoped the confrontation over Moscow's annexation of Crimea would not harm cooperation with Russia on international efforts to destroy Syria's chemical weapons.
"All I can say is I hope the same motivations that drove Russia to be a partner in this effort will still exist," Kerry told reporters in The Hague.
A large portion of the chemicals are to be destroyed on a U.S. ship, the Cape Ray but that process has not yet started and will take up to 90 days, Washington has said.
Syria has missed almost all deadlines agreed in the deal brokered by Kerry and Russian Foreign Minister Sergei Lavrov, whom Kerry met in The Hague for bilateral talks.
Lavrov repeated Moscow's position that Syria will meet its obligations under the deal.
"We have reason to believe that the deadlines will be respected and the chemical weapons will be removed from Syria by the middle of 2014," Lavrov said, as quoted by Russia's foreign ministry.
Plans for a joint mission between Russia and NATO to protect the Cape Ray that will destroy Syria's deadliest chemical weapons at sea have been cancelled due to tensions over Russia's annexation of the Crimea.
Kerry, who made no further allusion to Crimea in his remarks, noted that Syria had also missed a March 15 date for destruction of a dozen production and storage facilities.
"We have some real challenges ahead of us in these next weeks. We in the United States are convinced that if Syria wanted to they could move faster," he added.
Kerry confirmed that about half of Syria's declared chemical weapons arsenal has been shipped out or destroyed within the country.
"We are just about at the 50 percent removal mark. That is significant but the real significance would only be when we get all the weapons out," he said. (Reporting by Fredrik Dahl and Alissa de Carbonnel, Writing by Anthony Deutsch; Editing by Angus MacSwan)