The sound of explosions and occasional gunfire could be heard across the border from Kobani a day after Kurdish fighters managed to slow the advance of the terrorist group.

What appeared to be a rocket-propelled grenade struck a minaret in the center of the town, emitting a cloud of white smoke.

Activists said ISIS militants were carrying out a three-pronged attack from the eastern side of the town and that clashes were ongoing in the southern part.

The Syrian Kurdish enclave has been the scene of heavy fighting since late last month, with the better-armed ISIS terrorists determined to capture the border post.

The extremist group has carved out a vast stretch of territory from northern Syria to the outskirts of Baghdad and imposed a harsh version of self-declared Islamic caliphate ruling. The fighters have massacred hundreds of captured Iraqi and Syrian soldiers, terrorized religious minorities, and beheaded two American journalists and two British aid workers.

A U.S.-led coalition has been carrying out airstrikes against militant targets in and around Kobani for more than two weeks, and the town's fate has emerged as a major test of whether the air campaign can roll back the extremists in Syria.

The Britain-based Syrian Observatory for Human Rights said an ISIS suicide bomber detonated a car filled with explosives in the northern part of Kobani near the border with Turkey on Monday.

It said the car was headed to the border crossing between Kobani and Turkey. A Kurdish activist in the town, Farhad Shami, said the vehicle appeared to have exploded prematurely. It was not immediately clear whether there were any casualties.

Shami said coalition aircraft were flying over Kobani and had struck 10 times Sunday and Monday.

Fierce clashes on the Turkish border are going on as Ankara denied allowing Washington to use its bases against the ISIS group.US officials had earlier said Turkey would also host training for "moderate" Syrian rebels, in the hopes of finally creating a force capable of tackling IS on the ground.

"There is no new agreement with the United States about Incirlik," a Turkish government official told AFP of an air base in southern Turkey that the US wants to use to launch air strikes. "Negotiations are continuing" based on Turkish conditions previously laid out, the official added.

With the ISIS advancing on its doorstep, NATO member Turkey has come under intense pressure to take action as part of a US-led coalition that has been carrying out air strikes in Syria and Iraq.