Some 32 UN ambassadors began a week of crisis talks on Monday in an effort to rescue a mid-September world summit on extreme poverty, human rights, terrorism, proliferation and UN management reforms.

US Ambassador John Bolton, who had put forward more than 500 amendments or deletions to a 39-page draft text, submitted several letters, including ones on development and terrorism, explaining the US position.

"I'm optimistic that we have all the proposed amendments out on the table and we can engage in negotiations," Bolton told reporters during a break in the talks. "That's what they pay us to do."

But time is short and diplomats said conclusions would have to be reached this week so the document, which has been under discussion for six months, could be translated and submitted to more than 170 world leaders expected to attend the September 14-16 summit.

The session, called by UN Secretary-General Kofi Annan, is aimed at revitalizing the United Nations and approving new approaches to world issues in the 21st century.

The definition of terrorism, which has been discussed for eight years so it can be included in a binding treaty, is so contentious that Monday's meeting broke up into an evening sub-group to discuss it. The main thrust would be to outlaw attacks against civilians.

Bolton, in a letter to ambassadors, said the text should not "address military activities that are appropriately governed by international humanitarian law," an apparent reference to US soldiers in Iraq or Israeli armed forces.

But Arab nations and others insist the definition exclude the Palestinian struggle against Israel and include action of armed forces against civilians.

Bolton noted that Pakistan and Egypt, among others proposed amendments, not just the United States, which wants to focus on a commitments towards a treaty.

But in an obvious reference to the United States, Syria's U.N. ambassador, Fayssal Mekdad, told reporters," We started negotiations six months ago and we were thinking that we were reaching a good conclusion and suddenly someone comes and says 'this is rubbish' and they want to start line by line, word by word, sentence by sentence."

The United States has proposed changes on development that would remove references to the Millennium Development Goals, agreed by world leaders in 2000 and aimed at halving AIDS, extreme poverty and achieving universal primary education by 2015.

Instead the United States wants to substitute the phrase "internationally agreed development goals" and emphasize a 2002 agreement in Mexico spelling out the need for poor nations to improve investment climates.

In his letter to ambassadors sent on Friday, Bolton said that the United States backed the goals but not commitments on how to reach them, such as rich nations spending 0,7% of their gross national product for development.

"Let there be no doubt: the United States supports the development goals of the Millennium Declaration," Bolton wrote.

British Ambassador Emyr Jones Parry, who is representing the European Union, the only major group that in general backs the draft document, expressed optimism.

"People are putting forward sensible amendments. There is a debate engaged," he said. "I don't favor going through it line by line, bracket by bracket. We haven't got time for that."

South Africa was also optimistic. "We are used to the United States," South African Ambassador Dumisani Kumalo said. "We negotiate with them every year so this is normal." "But this is not a summit just of the United States," he said. "We'll get through this. We have no alternative."