GENEVA — Syria has delivered a consignment of chemical weapons materials for export and destruction overseas for the first time in more than two weeks, a delay that revived concerns about the country’s readiness and ability to meet newly extended deadlines for completing the task this month.

The delivery, completed on Friday, involved an unspecified volume of chemical agents, according to a statement by the Organization for the Prohibition of Chemical Weapons, the international monitor group helping the United Nations oversee the destruction of Syria’s chemical weapons arsenal. However, Friday’s consignment involved only a small volume of chemical agents, Michael Luhan, a spokesman for the agency, said in an interview.

Syria missed a February deadline for completing the shipment of all chemical weapons materials to be destroyed abroad and later agreed it would finish the job by April 27, so as to fulfill the agreement brokered by the United States and Russia, which calls for complete destruction of all elements of its chemical weapons program by the end of June.

A succession of deliveries in March increased the proportion of chemicals shipped out to about half the total, raising hopes that Syria could meet its April deadline. But the lapse of more than two weeks in deliveries has put that target in doubt.