The United States has begun delivering weapons to Syrian rebels over the past two weeks, which marks "a major escalation of the U.S. role" in the Syria conflict, a report said.

The move by the U.S. spy agency the Central Intelligence Agency (CIA) ended months of delay in lethal aid that the Obama administration promised long ago, a report published on the Washington Post's website quoted U.S. officials and Syrian figures as saying on Wednesday.

The shipments of weapons were delivered to Syrian rebels together with separate deliveries by the State Department of vehicles and other gear, the report said.

The arms shipments are limited to light weapons and other munitions that can be tracked, and the U.S. hopes that they "will boost the profile and prowess of rebel fighters in a conflict that started about 2 1/2 years ago."

New types of nonlethal gear, including vehicles, sophisticated communications equipment and advanced combat medical kits, are also being shipped to the rebels, at a time when the Obama administration is threatening to attack Syrian government for its alleged chemical attack on Aug. 21, that the U.S. claims killed more than 1,400 people near the capital of Damascus.

The latest U.S. aid is aimed at supporting rebel fighters under the command of Salim Idriss, head of the Supreme Military Council, a faction of the disjointed armed opposition, the report said.

The Obama administration pledged in April to provide arms to Syrian rebels, but such efforts have lagged due to fears that these weapons could fall into hands of the extremist militants fighting the government of President Bashar al-Assad.

The CIA shipments of arms flow through a network of clandestine bases in Turkey and Jordan, the report said.

A Syrian opposition official was quoted as saying that the U.S. remains reluctant to provide the rebels what they most desire: antitank and antiaircraft weapons.