In a commentary in the daily International Herald Tribune Friday, Annan said the panel would "focus primarily on threats to peace and security" and the challenges ahead for the world body.

Although he did not explicitly mention the war in Iraq, he noted that "The events of the past year have exposed deep divisions among members of the United Nations on fundamental questions of policy and principle."

Annan, who was opposed to the US-led campaign to topple Saddam Hussein, said in his commentary. "When is the use of force permissible - and who should decide?

"Does it have to be each state for itself, or will we be safer working together?" he added. "Is "preventive war" sometimes justified, or is it simply aggression under another name?"

He said the 16-member panel, which is being headed by former Thai prime minister Anand Panyarachun, would hopefully complete its report by autumn 2004, in time for the UN General Assembly.

Other members of the panel include former Russian prime minister Yevgeny Primakov, Arab League Secretary General Amr Musa, former Chinese foreign minister Qian Qichen and Brent Scowcroft, the national security advisor to former US President George Bush.