Islamic State militants are retreating in parts of the northern Syrian town of Kobane in the face of US-led air strikes, a Kurdish official has said.

Idriss Nassan told the BBC IS had lost control of more than 20% of the town on the border with Turkey in recent days.

Activists say more than 600 people have been killed since the jihadist group launched its assault a month ago.

On Wednesday, US and European leaders agreed on the need to do more to stop the advance of IS in Iraq and Syria.

In a video conference, US President Barack Obama and the leaders of the UK, France, Germany and Italy said they would step up support for an "inclusive political approach" in Iraq and training for local forces.

Mr Nassan, deputy head of Kobane's foreign relations committee, said the Kurdish the Popular Protection Units (YPG) had made progress against IS in the town since the US-led air strikes were stepped up.

"Maybe in the few past days [Islamic State] was controlling about 40% of the city of Kobane, but now... less than 20% of the city is under control of [IS]," he said. "[On Wednesday], YPG started cleaning [up]operations in the east and south-east of Kobane."

A journalist in Kobane, Abdulrahman Gok, told the Reuters news agency on Thursday: "We walked past some (YPG) positions in the east yesterday that were held by IS only two days ago."

"Officials here say the air strikes are sufficient but ground action is needed to wipe out IS. YPG is perfectly capable of doing that but more weapons are needed," he added.

Pentagon spokesman Rear Admiral John Kirby said the situation was fluid, with pockets in the town still held by IS.

Kobane was still in danger of falling because increasing numbers of jihadists were joining the battle, he warned.

"The more they want it, the more resources they apply to it, the more targets we have to hit," he added. "We know we've killed several hundred of them."

(BBC)