(CNN) -- A Chinese ship arrived to escort ships picking up chemical weapons materials from Syria on Tuesday, China's state-run Xinhua news agency reported Wednesday.
The frigate Yancheng is working closely with other ships from Russia and Europe, the agency reported, citing a Beijing Foreign Ministry statement.
The international effort to dismantle Syria's chemical weapons program reached a milestone Tuesday when a Danish commercial ship picked up the first batch of important chemical materials, the group overseeing the work said.
The "priority chemical materials" loaded at the Syrian port of Latakia, and the ship -- escorted by Danish and Norwegian warships -- left for international waters, the Joint Mission of the Organization for the Prohibition of Chemical Weapons and the United Nations said Tuesday.
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The ship will remain at sea until more chemical materials are made available at the Latakia port for pickup. The chemicals eventually will be taken to locations outside Syria for destruction, the group said.
Tuesday's move comes a week after a deadline for the first chemical materials to leave Syria. The mission blamed the delay on "the continuing volatility in overall security conditions" and on "logistical challenges coupled with inclement weather."
Syria's chemical weapons are targeted for removal and elimination by the end of June.
Syria agreed to have its program dismantled under international pressure last year over allegations the Syrian government used sarin nerve gas in an August 21 attack on a Damascus suburb. U.S. officials said at least 1,400 people died in the attack. Syria denied responsibility, blaming rebel forces.