Air strikes 'not enough' to stop ISIL: US general

The bombing campaign being conducted by the US, Australia and coalition partners will not be enough to wipe out ISIL, the US' top general has claimed.

General Martin Dempsey, the chair of the US Joint Chiefs of Staff, says there needs to be a "ground component" to the campaign, the New York Post has reported.

US President Barack Obama has previously ruled out putting ground troops into Iraq, although Australia has sent a special forces component to reportedly act as military advisers to Iraqi forces.

Gen Dempsey has said it will take 12,000 to 15,000 troops to reclaim territory in Iraq and Syria lost to ISIL's self-proclaimed Caliphate.

Syrian, Iraqi and Kurdish fighters have been battling ISIL forces on the ground, with mixed success.

ISIL's troops are estimated to number up 30,000, including foreign recruits.

Up to 60 Australians are believed to be fighting with extremist organisations in Iraq and Syria.

While coalition leaders including Mr Obama and Australian Prime Minister Tony Abbott have repeatedly played down the probability of Western ground troops being used in combat roles, a number of commentators and opposing politicians have raised the spectre of "mission creep" - gradually building up Western participation in the region.

Other pundits believe ISIL is attempting to goad the West into embarking on a ground war, which they believe would galvanise the local Sunni Muslim population into following the extremist group's banner.

Meanwhile, British warplanes flew their first mission over Iraq since the nation's parliament authorised strikes against ISIL, but returned without bombing.

Royal Air Force Tornado GR4 combat jets returned to Britain's RAF Akrotiri base on Cyprus without dropping any of their load of Paveway IV laser-guided bombs, after a seven-hour mission that began before dawn from the Mediterranean island.

"On this occasion no targets were identified as requiring immediate air attack by our aircraft," a ministry spokesman said.

However, the jets' surveillance gathered information that will "help acquire potential targets for future operations, either by aircraft or Iraqi ground forces," the spokesman said.

British lawmakers on Friday voted overwhelmingly to join the US-led air strikes in northern Iraq following a formal request for help from the Iraqi government.

The campaign against the Islamist group gathered pace this week, as Belgium and Denmark agreed to join the bombing and Britain's lower house of parliament voted in favour of air strikes in Iraq.

A fresh round of bombings by the US, Saudi Arabia, Jordan and the United Arab Emirates in recent hours has damaged an IS-held airfield, a garrison and a training camp near the group's headquarters in Raqa, the Pentagon said.

In Iraq, a fighting position and four armed vehicles were hit, it added.

Australian fighter jets are in Dubai and expected to join combat operations within days after Mr Abbott briefs Cabinet.

Additional reporting by AFP.