George Clooney's humanitarian organization has donated $500,000 to a U.N. food aid agency to help it continue flights in Sudan's troubled Darfur region, the agency said Thursday. The Rome-based World Food Program said that the money came from Not On Our Watch, founded by Clooney and other stars - including Brad Pitt and Matt Damon - to press concerns about Darfur. The group has raised more than $9.3 million for the region. Earlier this week, the World Food Program warned that lack of funds this year would force a halt to the flights ferrying urgently needed supplies in the region at the end of March.

"This is a critical time for the program. Without immediate additional funding, humanitarian aid in the region will be crippled," Clooney was quoted as saying in a U.N. statement.

Over the past year, the World Food Program has been feeding between 2 and 3.2 million people in Darfur. The number of people in need could double with the May-October rainy season, the agency said.

"This contribution will make a difference to the millions of vulnerable women and children trapped there, and we hope it will inspire other donations," WFP's Executive Director Josette Sheeran said.