More efforts pledged to fight ISIS

The US is leading the fight against the growing presence of ISIS militants in the Middle East.

FILE: Demonstrators at a rally supporting Kurdistan hold placards protesting against the Islamic State of Iraq and Syria (ISIS) in front of the White House on 16 August, 2014. Picture: AFP.

LONDON - International efforts to combat Islamic State of Iraq and Syria (ISIS) militants have taken on added urgency after the beheading of a British aid worker and the threat to kill a second UK hostage.

The murder of David Haines comes amid moves to form a broad coalition against the terror group which has grabbed large swathes of territory in Syria and Iraq.

The US says several countries in the Middle East have offered to join airstrikes against the militants and Australia says it will send aircraft and personnel.

US President Barack Obama on Saturday strongly condemned "the barbaric murder" of Briton David Haines by Islamic State militants after the group released a video purporting to show the beheading of the aid worker.

"The United States stands shoulder to shoulder tonight with our close friend and ally in grief and resolve," Obama said in a statement.

"We will work with the United Kingdom and a broad coalition of nations from the region and around the world to bring the perpetrators of this outrageous act to justice, and to degrade and destroy this threat to the people of our countries, the region and the world."

Britain's Prime Minister David Cameron says the UK will help destroy IS and extinguish what he calls a terrorist threat to the global community.

Citizen could have carried out the killings.

Speaking after chairing a meeting of the government's emergency response committee in London, Cameron called the killing of Haines, a 44 year-old Scottish aid worker, callous and brutal and hailed him as a "British hero."

"We will hunt down those responsible and bring them to justice no matter how long it takes," he said, calling IS "the embodiment of evil" and saying his government was prepared "to take whatever steps are necessary" against the militants.

US Secretary of State John Kerry has been touring the Middle East to try to secure backing for US efforts to build a coalition to fight the Islamic State militants who have grabbed territory in Syria and Iraq.

The United States resumed air strikes in Iraq in August for the first time since the 2011 withdrawal of the last US troops fearful the militants would break the country up and use it as a base for attacks on the West.

The addition of Arab fighter jets would greatly strengthen the credibility of what is a risky and complicated campaign.

"We have countries in this region, countries outside of this region, in addition to the United States, all of whom are prepared to engage in military assistance, in actual strikes if that is what it requires," Kerry said.

"And we also have a growing number of people who are prepared to do all the other things," he said in remarks broadcast on Sunday on the CBS program "Face the Nation."

Offers of Arab air participation have been made both to US Central Command overseeing the American air campaign and to the Iraqi government, a senior State Department official said.

Australia became the first country to detail troop numbers and aircraft to fight the militants in Iraq. It said it would send a 600-strong force and eight fighter jets to the region but did not intend to operate in Syria.

Russia, at odds with the West over Ukraine, has said any air strikes in Syria would be an act of aggression without the consent of President Bashar al-Assad or an international mandate.

Britain has often been the first country to join US military action overseas and is under pressure to get much tougher with IS after video footage of the killing of Briton David Haines by the militants was released on Saturday.

In footage consistent with the filmed executions of two American journalists, James Foley and Steven Sotloff, in the past month, they also threatened to kill another British hostage.

Kerry will meet British Foreign Secretary Philip Hammond during a conference on Iraq in Paris on Monday. The conference brings Iraqi authorities together with about 30 countries and organisations to coordinate their response to Islamic State.