Fighter jets, bombers and unmanned drone planes hit the IS militants in several locations south of Kobane on Monday and Tuesday, destroying four armed vehicles, anti-aircraft artillery, a tank and a jihadist "unit," Central Command, which is overseeing the air war, said in a statement.

The strikes came as the IS group extremists appeared on the verge of seizing control of the strategic town, where the outnumbered Kurdish defenders have been locked in a desperate fight for weeks.

The fall of Kobane to the IS group would mark a major victory for the extremists, who aim to take control over a long stretch of the border with Turkey for their self-proclaimed "Islamic caliphate."

At least 412 people, more than half of them jihadists, have been killed in and around Kobane since mid-September, according to the Syrian Observatory for Human Rights, a Britain-based monitoring group.

US-led forces also carried out four additional air raids elsewhere in Syria and four strikes in Iraq on Monday and Tuesday, it said.

The other air attacks in Syria targeted IS militants southwest of Rabiyah, west of Al-Hasakah and northeast of Deir Ezzor, where US-led planes hit a production facility for homemade bombs.

Warplanes from Saudi Arabia and the United Arab Emirates took part in the bombing raids in Syria, the military said, without providing more details.

In Iraq, the air raids focused on IS armed vehicles and militants northeast of Sinjar. Aircraft from Belgium also joined the air raids in Iraq, it said.

All aircraft "safely exited" the strike areas in Syria and Iraq, Central Command said.