BEIRUT (AP) — A spokesman for U.S-backed Syrian rebels and an activist group say the rebels have seized a small military base that was held by the Islamic State group near the Iraqi border.

Wednesday's capture of the Hamdan air base, which has served as an IS outpost, came just hours after the launch of a new offensive seeking to cut the militants' transit link between Syria and Iraq.

Mozahem al-Saloum, spokesman for the Pentagon-trained New Syrian Army, says there was extensive air support from the U.S.-led international coalition during the operation and that airborne fighters were dropped onto the southern edge of the border town Boukamal to help the rebel advance.

The Britain-based Syrian Observatory for Human Rights says several rebel factions were involved, bringing ground troop numbers to several hundred.