Coalition ratcheting up pressure on Isis in Syria: Obama

President Barack Obama. Photo / AP

United States President Barack Obama says the coalition battling Isis (Islamic State) jihadists is intensifying its campaign against the group's base in Syria.

Obama addressed the media after a briefing at the Pentagon with military brass on efforts to dismantle the jihadist group, which has taken over large swathes of Iraq and Syria.

The high-level talks came after coalition air strikes that hit Isis' de facto capital Raqqa in Syria over the weekend - some of the heaviest bombing since it began targeting Isis in Syria in September last year.

"We're intensifying our efforts against [Isis'] base in Syria. Our air strikes will continue to target the oil and gas facilities that fund so much of their operations," Obama said.

Obama cautioned the fight would likely face setbacks.

He said more than 5000 air strikes had been carried out against the group, eliminating "thousands of fighters, including senior [Isis] commanders".

Meanwhile, Iraqi armed forces and allied militia were fighting to reach the gates of Fallujah, in the first major attempt to recapture a city in the largely Sunni province of Anbar since most of it fell to Isis last year.

The Government of Haider al-Abadi, the Iraqi Prime Minister, is trying to reverse gains by Isis after it seized the state capital, Ramadi, in May. Despite Baghdad's promises that its forces would recapture Ramadi swiftly, Shia militia that are far more powerful than the government forces they operate alongside said last month that an attack on Fallujah was the priority.

Fallujah lies between Ramadi and Baghdad, and the new offensive is aimed at protecting the capital and cutting Isis supply lines.

- Telegraph Group Ltd, AFP