PARIS (AFP) - Humanitarian organisations are preparing to launch a fundraising appeal for US$500 million (S$674million) for the crisis created by the Islamic State in Iraq and Syria (ISIS), the United Nations children's agency UNICEF said on Monday.

The announcement came a day ahead of a meeting in Paris of the US-led coalition of countries working to defeat the militant group in Iraq and Syria.

"The humanitarian situation in Irak is close to disaster! We urgently need extra resources in order to continue assistance," Philippe Heffinck, UNICEF's representative in Iraq, said in a statement in French.

According to the UN agency, eight million Iraqis are in urgent need of humanitarian aid, in particular the roughly three million people who have been forced to flee their homes since the start of the IS offensive in June 2014.

Access, however, has been hampered by the fighting and a lack of funding is now even threatening such humanitarian assistance as has been possible, UNICEF said.

As a result, all those organisations currently active in Iraq would in Brussels on Thursday to launch "a fundraising appeal for nearly US$500 million to cover relief operations over the next six months", the agency added.

The US-led coalition of some 60 nations was formed last year after ISIS went on a rampage across Iraq and Syria, seizing key territory upon which it declared a caliphate.

Ministers from Turkey, Saudi Arabia, Qatar, and the United Arab Emirates are expected to be among 24 participants attending the anti-ISIS coalition meeting in Paris.

The main focus of the meeting will be the situation in Iraq, where ISIS seized the city of Ramadi two weeks ago in the biggest blow to the coalition since it began bombarding militants positions in August.