BEIRUT -- U.S.-led coalition warplanes carried out as many as 30 airstrikes overnight against Islamic State militants in and around the group's de facto capital in northeastern Syria, activists said Sunday.
The Britain-based Syrian Observatory for Human Rights said the strikes targeted IS positions in the city of Raqqa as well as the Division 17 air base, which the militants seized earlier this year from government forces.
The monitoring group, which relies on a network of activists inside Syria, reported at least 30 coalition strikes in all. The Local Coordination Committees, an activist collective, also confirmed the airstrikes. Neither group had casualty figures.
There was no immediate confirmation from the U.S. military.
The American-led coalition began targeting Islamic State militants in Syria in September, expanding an aerial campaign already hitting the extremist group in Iraq.
Many of the U.S. airstrikes in Syria have targeted IS fighters who are attacking the predominantly Kurdish town of Kobani on the Turkish border.
The Observatory said that at least 50 IS militants were killed on Saturday and early Sunday in clashes with Kurds and in coalition airstrikes. Eleven Kurdish fighters were also killed, according to the Observatory.
Idris Nassan, a Kurdish official from Kobani, said by telephone that tens of IS militants were killed, but he did not have a concrete figure.
IS has been attacking Kobani since mid-September. The militants' offensive has bogged down, and the Syrian Kurds -- backed by their Iraqi brethren with heavy weapons -- appear to have seized the momentum and to have begun pushing the jihadis back.
