Kurdish forces are driving Islamic State (IS) militants out of Kobane – a strategic town in the push to create a Caliphate – but it could still fall, military officials report.

Idriss Nassan told the BBC that jihadists are now controlling "less than 20 per cent" of the city, after advancing into Kobane last week.

Yesterday Pentagon intelligence said that "several hundred ISIL fighters" had been killed in and around the city through US-led airstrikes.

IS has been fighting for Kobane since mid-September. 18 have been launched on the city over the past two days.

"We know we're having some success. We know we're making progress. But it's going to take a long time," Pentagon spokesman John Kirby said on Wednesday.

"We are striking the targets around Kobane for humanitarian purposes...Given the circumstances associated with the defence of that town, there was a need for additional fire support to go in to try to relieve the defenders and to buy some white space.

"We have picked up the tempo and the intensity of the air strikes in order to provide that white space."

Kirby warned that IS could still seize control of the city. "Kobane could still fall, it could very well still fall," he said.

"ISIL has made no secret of the fact that they want that town... and so they have continued to flow fighters to Kobane."

As a border crossing with Turkey, Kobani is a strategic region, and IS and other Islamist militant groups in Syria have been attempting to capture the town since August 2013.

During a meeting with international defence chiefs on Tuesday, President Obama warned the US-led mission against ISIS will be a "long-term campaign".

"There will be days of progress and there are going to be periods of setback," he said.