U.S. Secretary of State John Kerry said on Sunday the United States was deeply concerned about what he called the "tragedy" in the Syrian town of Kobani.

U.S. Secretary of State John Kerry said on Sunday the United States was deeply concerned about what he called the "tragedy" in the Syrian town of Kobani, where militants of the so-called 'Islamic State of Iraq and the Levant' (ISIL) have been tightening their grip.

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

"Obviously we are all very concerned about the reports of gains in Kobani and we're closely monitoring the situation. In fact, we're not just monitoring it, we've been deeply engaged with strikes in the last days and today there were more strikes," said Kerry.

"There was news today that they are continuing to hold it down, it has not been taken in completion, parts of it have."

Kurdish forces defending Kobani at the border with Turkey urged a U.S.-led coalition to escalate air strikes on ISIL terrorists.

A group that monitors the Syrian civil war said the Kurdish forces faced inevitable defeat in Kobani if Turkey did not open its border to let through arms - something Ankara has so far appeared reluctant to do.

Kerry said more than 60 partners have committed to joining the U.S. effort to defeat ISIL.

"Kobani is one community and it's a tragedy what is happening there and we don't diminish that, but we have said from day one it was going to take a period of time to bring the coalition thoroughly to the table," said Kerry.