The world's chemical weapons watchdog says more than 49 percent of the raw materials for Syria's poison gas and nerve agent program scheduled for destruction have been shipped overseas, with the rest expected to leave by the end of April.

The Organization for the Prohibition of Chemical Weapons said in a report to the United Nations, obtained Wednesday by The Associated Press, that the total percentage of chemicals either removed or already destroyed inside the war-torn country is 53.6 percent.

The report said Syria pledges to remove all chemicals by April 13, except for those in areas "that are presently inaccessible," which face an April 27 deadline.

The international community, shocked by a chemical attack in August that killed hundreds near Damascus, aims to remove and destroy 1,300 metric tons of chemicals by June 30. The August attack was blamed on the government of Syrian President Bashar Assad, which denied involvement.

In a cover letter to the new OPCW report, addressed to the UN Security Council, UN Secretary-General Ban Ki-moon said two incidents this month of rocket attacks on the Syrian port of Latakia "did not stop the removal operations."

But Ban urged speed, saying, "The precarious and unstable nature of the security situation further underlines the importance of expediting the removal of chemical weapons material from the territory of the Syrian Arab Republic as quickly and as safely as possible."

The most toxic chemicals, including mustard gas and raw materials for making the nerve agent sarin, are being put on Danish and Norwegian cargo ships at the port of Latakia and will be transferred to a U.S. ship, MV Cape Ray, in the Italian port of Gioia Tauro. The Cape Ray is equipped with two machines that will render the chemicals inert.

Syria's ambassador to the UN, Bashar Ja'afari, on Wednesday said fighters' attempts to shut down the port and affect the chemical shipments were "trying to create a catastrophe."

Syria's government missed a December 31 deadline to remove the most dangerous chemicals in its stockpile and a February 5 deadline to give up its entire stockpile of chemical weapons. The Assad regime cited security concerns and the lack of some equipment but has repeated that it remains fully committed to the process.

Syria's conflict, now in its fourth year, has killed more than 140,000 people, displaced at least a quarter of its pre-war population of 23 million and triggered a humanitarian crisis across the region.