US Secretary of State John Kerry will meet foreign ministers from around the world in Paris on Monday to discuss how to defeat Islamic State (IS) militants.
About 40 countries, including 10 Arab states, have signed up to a coalition to help fight IS in Iraq and Syria.
French President Francois Hollande said the beheading of a British aid worker showed the world must act against IS.
Meanwhile, France says it has joined the UK in carrying out surveillance flights over IS positions in Iraq.
“This very morning, the first reconnaissance flights will be carried out in agreement with the Iraqi and Emirati authorities,” Defence Minister Jean-Yves Le Drian told French troops on Monday at the Al-Dhafra base in the United Arab Emirates.
Britain revealed in August that Tornado jets and surveillance aircraft were involved in intelligence gathering.
Several Arab countries have offered to take part in air strikes on IS fighters in Iraq, US officials say.
Mr Kerry said he was “extremely encouraged” by promises of military assistance to tackle the militant group.
He spoke after a whirlwind tour of the Middle East to try to drum up support for a plan of action unveiled by US President Barack Obama last week.