John Kerry has said the US is deeply concerned about the "tragedy" in the Syrian town of Kobane, where self-declared jihadist fighters have been tightening their grip.

However, Kobane does not define the strategy for the coalition with regard to the Islamic State of Iraq and the Levant (ISIL), the US secretary of state said in comments on Sunday.

Speaking at a conference in Cairo on the rebuilding of the Gaza Strip, Kerry said it would take time to bring a coalition fully together to confront ISIL, adding that the focus must first be on Iraq while degrading ISIL in Syria.

"Kobane does not define the strategy for the coalition in respect to Daesh [ISIL in Arabic]. Kobane is one community and it is a tragedy what is happening there. And we do not diminish that," Kerry said.

"But we have said from day one that it is going to take a period of time to bring the coalition thoroughly to the table to rebuild some of the morale and capacity of the Iraqi army. And to begin the focus of where we ought to be focusing first which is in Iraq. That is the current strategy."

Kurdish forces defending Kobane at the border with Turkey urged a US-led coalition to escalate air strikes on ISIL fighters.

Kerry said more than 60 partners have committed to joining the US effort to defeat ISIL, which has declared a "caliphate" in parts of Iraq and Syria it controls.

In another development, US defence officials told the Associated Press news agency that Turkey had agreed to let US and coalition forces use its bases, including Incirlik airbase, which is within 160km of the Syrian border, for operations against ISIL in Syria and Iraq.

US officials also confirmed that Turkey had agreed to train Syrian moderate forces on Turkish soil.

A Turkish government official told the AP on Sunday that Turkey put the number at 4,000 opposition fighters and said they would be screened by Turkish intelligence.

The US administration had been pressing Turkey to play a larger role against ISIL, who have taken control of large expanses of Syria and Iraq, including territory on Turkey's border, and sent refugees fleeing into Turkey.