There are now some 100 goodwill ambassadors, chosen by various UN agencies, and nine "Messengers of Peace" appointed by the UN secretary-general.

UK author and humorist Peter Ustinov spoke

The ambassadors first met October 2000, when Susan Sarandon, Geri Halliwell and Somali supermodel Waris Dirie discussed the difficulties of their roles in open session.

But this year discussions were held behind closed doors and only the opening session, at which Annan and a few celebrities spoke, was open to the press.

'Adversaries'

Harry Belafonte used the opening session to defend the UN from its detractors.

"We have underestimated the power, and the evil will, of our adversaries," he said.

"There are forces who are immoral, and those who would oppose us in what we do."

And Belafonte urged the celebrities to use their platforms more effectively, and to do their jobs "with courage".

Angelina Jolie, who became an envoy for the UN High Commissioner for Refugees (UNHCR) a year ago, said she was stunned to find out through her work that 20 million people had fled their countries.

Her role has taken her to Cambodia, Pakistan, Colombia and Sierra Leone.

"I don't know really the difference I've made," said Jolie.

"I know how it's changed my life and made me a better person. It's taught me to value my family more, to value life more, to value other people more."

At a closed session, Elie Wiesel, a Holocaust survivor Nobel Peace Prize winner, urged fellow celebrities never to forget the world's victims, UN officials said.