The Syrian Observatory for Human Rights also reported intensifying clashes between Kurdish fighters defending Kobane and IS jihadists in the south of the town, which lies on the Turkish border.
Kurdish activist and Kobane resident Mustefa Ebdi reported at least seven international air strikes overnight.
He said the explosions could be heard 20 kilometres from Kobane, and shook the cars of people with him on the border between Turkey and Syria.
In southern Kobane, meanwhile, the Britain-based Observatory said fierce clashes underway for the past three days were continuing with reports of injuries on both sides.
The group said Kurdish YPG forces and Iraqi Kurdish peshmerga fighters were also shelling IS positions during the clashes.
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Ebdi also reported the clashes, saying the situation in Kobane "has progressed from defence to attack because of the air raids and the support the peshmerga and the (Arab rebel) Free Syrian Army are giving the YPG fighters."
"The Kurdish fighters are advancing slowly because of the mines laid by IS. They are trying to retake territory," he said.
The Islamic State began advancing on Kobane two months ago, hoping to seize the small Kurdish town and cement their grip over a large stretch of the Syrian-Turkish border.
But US-led air strikes, along with fierce fighting by YPG troops backed by around 150 Iraqi peshmerga, have so far prevented IS from overrunning the town completely.
The Observatory said Sunday that the toll since fighting began had risen to 1,153, including 27 civilians, 398 Kurdish YPG fighters, 16 non-Kurdish rebels backing the YPG and 712 Islamic State fighters.