Two Iraqi soldiers died in the fighting and no Americans were killed, the military said in a written response, confirming a media report. It did not provide more details.

Reuters witnesses in Ramadi, 115km west of Baghdad, said there were heavy clashes last week between US forces and insurgents inside Ramadi but could not independently confirm such a high number of insurgents killed.

Ramadi is a stronghold of Sunni Arab insurgents fighting US and Iraqi forces and the Shia and Kurdish-led government in Baghdad.

Despite large-scale US support, Iraq and Afghanistan rank among the world's 10 most vulnerable states, according to a private survey being released yesterday.

In its second annual "failed states" index, Foreign Policy magazine and the Fund for Peace concluded that Sudan is the country under the most severe stress because of violent internal conflict.

Eleven of the 20 most vulnerable countries of the 148 examined in the survey are in Africa. The Democratic Republic of the Congo and Ivory Coast, both chronically volatile in recent years, ranked second and third.