Syrian opposition figures voiced disappointment to US Secretary of State John Kerry as they met him on the sidelines of the United Nations General Assembly.

Syrian opposition figures voiced disappointment to US Secretary of State John Kerry as they met him on the sidelines of the United Nations General Assembly.

Syrian opposition chief Ahmad Jarba led a four-strong delegation to meet Kerry, as the foreign backed opposition militants were fighting extremist groups.

Opposition militants are now fighting on two fronts, a senior State Department official said, highlighting that as well as battling the Syrian government, opposition military chief General Selim Idriss and his forces were locked in combat against al-Qaeda affiliated groups.

"Right now there's a real firefight going on up along the border Turkey and Syria between Al-Qaeda extremists and forces loyal to Selim Idriss," he said.

"That is battle that is ongoing right now, and it's very confusing," he said, adding Idriss militants were bringing in reinforcements but it was "a hard slog."

"It's the hardest fighting we've ever seen between Selim Idriss's elements of the Free Syrian Army and the Islamic State of Iraq in the Levant," he added.
"The extremists are doing the government's work now."

"They certainly did express disappointment that there hadn't been a military strike," the official said, after Obama last month backed away from taking military action against Syria.

The opposition also "wanted a reaffirmation of our stance concerning (President) Bashar al-Assad's legitimacy or lack thereof. Which Secretary Kerry gave them both barrels blazing."