GENEVA — After lengthy delays in loading its chemical weapons for destruction abroad, Syria has completed delivery of another shipment that brings the total to almost two-thirds of its arsenal, the international watchdog overseeing the process reported on Monday.

The delivery of chemical agents to the Syrian port of Latakia, completed on Sunday, was the second in three days. It raised the share of Syrian chemical agents handed over for destruction to slightly more than 65 percent, the Organization for the Prohibition of Chemical Weapons said in a statement from its headquarters in The Hague. The country has now delivered a bit more than 57 percent of its most dangerous, so-called priority one, chemicals, and 82 percent of less toxic, priority-two chemicals, said Michael Luhan, a spokesman for the organization.

The shipment was “necessary and encouraging,” the organization’s director general, Ahmet Uzumcu, said, but he made clear that it had not dispelled concerns about whether Syria would meet its deadline for completing the destruction of chemical agents by the end of April.

“Both the frequency and volumes of deliveries have to increase significantly to restore alignment of actual movements against the projected time frame” for completing the destruction of chemical weapons, Mr. Uzumcu said.