Islamic State (IS) fighters may have captured weapons airdropped by the US near the Syrian town of Kobane, intended for the Kurdish forces defending it against the jihadists' onslaught.

A video posted on YouTube on Tuesday by a group calling itself "A3maq News" purports to show airdropped supplies in the hands of the extremist group. The footage shows a masked and armed militant examining a package attached to a parachute. Later, he looks into crates containing various munitions, including RPG rounds and grenades.

The video could not immediately be independently verified, but A3maq News has previously posted IS-linked content and the some of the weapons seen in the video appear to match those possessed by Iraq's Kurdistan Regional Government (KRG), which supplied the arms.

The grenades seen at 1:28 in the video are reported to be German-made. Berlin sent 10,000 grenades to Iraqi Kurdistan in August as part of a consignment of military aid provided to the KRG's peshmerga fighters, according to publicly available German government documents.

Additionally, US Central Command confirmed in a statement on Monday that one airdropped bundle had missed its target,. However, CentCom said it had been destroyed in a follow-up airstrike to stop it falling into enemy hands.

American C-130 planes delivered weapons, ammunition and medical supplies provided by the KRG to People's Protection Units (YPG) fighters at dawn on Sunday, according to a CentCom statement. The operation was intended to "enable continued resistance against ISIL's attempts to overtake Kobane," CentCom added, using the former name for the Islamic State.

YPG spokesperson Redur Xelil told Reuters that the weapons would "help greatly" in the fight against IS. "The military assistance dropped by American planes at dawn on Kobane was good and we thank America for this support," he said.

Kobane is surrounded on three sides by IS and is bordered to the north by Turkey. The Turkish government has thus far refused repeated requests to open a land corridor allowing humanitarian and military supplies into the town, leading to accusations of tacit complicity in the IS assault on the Kurds, whose struggle for greater autonomy has long been a thorn in Ankara's side. However, on Monday it announced that it would allow Iraqi Kurdish fighters to cross the border to the town.

The airdrops were the first of their kind, but the US launched a series of airstrikes on IS targets in August, then extended operations into Syria in September. American planes have now carried out more than 135 airstrikes against IS in Kobane, according to the Centcom statement, which it says are indicated to have "slowed ISIL [S] advances into the city, killed hundreds of their fighters and destroyed or damaged scores of pieces of ISIL combat equipment and fighting positions."