At least 35 jihadists from the Islamic State group were killed in air strikes by a U.S.-led coalition overnight in northern and northeastern Syria, a monitor said Saturday.

The Syrian Observatory for Human Rights said 30 jihadists were killed around the town of Shadadi in northeastern Hasakeh, and another five outside the embattled town of Kobane, on the border with Turkey in northern Aleppo province.

The group said the strikes had destroyed some military materiel belonging to IS, which fired dozens of shells into the town on Friday after advancing to its outskirts.

An activist from the town, Mustafa Ebdi, also reported the strikes.

"They hit last night mostly on the eastern front," he said.

The raids followed a day of relentless bombardment of Kobane by IS forces who have surrounded the town, Syria's third largest Kurdish town.

Both Ebdi and the Observatory said IS forces had fired at least 80 shells into Kobane on Friday, as they attempted to force their way into the strategic border town.

Ebdi said Kurdish forces working with Arab rebels were able to repel an evening attack by IS jihadists, but fighting was ongoing.

The Observatory too reported heavy fighting on Saturday morning, particularly on the southwestern front, adding that IS was continuing to shell the town.

There was no immediate death toll from the fighting overnight.

But Ebdi said there was some optimism among the fighters in the town on Saturday.

"Daesh fighters were saying they would be praying Eid prayers in Kobane," he said, using the Arabic acronym for IS and referring to the Muslim Eid al-Adha festival being marked on Saturday.

"But so far they have failed to enter the town."

Later on Saturday, the U.S. military said U.S. and Arab warplanes pounded Islamic State positions in Syria overnight, targeting fighters, artillery and combat equipment in nine airstrikes.

U.S. bombers and fighter jets also carried out five airstrikes against the IS group in Iraq.

The United States was joined by Jordanian, Saudi and UAE warplanes in the attacks inside Syria, which involved a mix of fighter aircraft and drones.

Four of the airstrikes were around Kobane, a town along the Syrian border with Turkey that has been under attack by IS fighters.

Two of those strikes hit a large IS unit, a building, three artillery positions and an IS vehicle east of Kobane, which also is known as Ain al Arab, U.S. Central Command said.

South of Kobane, a small IS unit, an armored personnel carrier, and a vehicle were struck in two other air attacks.

The warplanes also struck an IS depot and logistics complex in Hasakeh, where 30 jihadists were reported killed.

Centcom said strikes also damaged the Taqba Airfield southwest of Raqa and another destroyed an artillery piece west of there.

Two airstrikes southeast of Deir Ezzor destroyed a tank and a vehicle.

IS began its advance towards Kobane on September 16, hoping to seize the strategic town and cement its grip over a long stretch of the Syrian-Turkish border.

The fighting has prompted a mass exodus of residents from Kobane and the surrounding countryside, with the Observatory estimating around 300,000 people have been displaced.

Many of those, at least 186,000 according to the Turkish government, have fled over the border into Turkey.