Prime Minister Haider al-Abadi hit out at the global community for its "failure" to roll out sufficient support, after the shock loss of the key city of Ramadi that sparked blame-trading between members of the US-led coalition carrying out air raids against the jihadists.
The meeting of some 20 coalition ministers comes as Iraq is trying to win back control of Ramadi, whose seizure by IS militants two weeks ago struck the biggest blow to the coalition since it began striking jihadist positions in August.
Abadi, who is to outline his plans to liberate the Sunni province of Anbar and its capital Ramadi, is also facing pressure for Baghdad to be more inclusive of the Sunni minority - seen as key to winning the battle.
But the Iraqi prime minister wants more from his partners, saying most of the IS fighters who have seized large swathes of Iraq were now foreign and therefore an "international problem."
More From This Section
He said that until recently, around six out of 10 fighters were Iraqi and the remainder foreign, whereas the proportion was now reversed.
The international community has to explain "why so many terrorists are from Saudi Arabia, why so many from the Gulf, why so many from Egypt, why so many from Syria, and Turkey and from European countries?"
His criticism came as IS claimed responsibility for a suicide attack on an Iraqi police base north of Baghdad yesterday that killed at least 37 people, mostly officers.
Shortly after capturing Ramadi, the jihadists seized the historic Syrian city of Palmyra in what appeared to swing the momentum in their favour after months on the back foot there.
The diplomat said the Syrian regime was "greatly weakened", giving impetus to the need to find a political solution to the four-year war.
"We can't lose sight of the fact that without dealing with the Syrian situation, it will be very hard to stabilise Iraq," the diplomat said.