US President George W Bush has defended his policies on the Middle East at the annual UN General Assembly gathering of world leaders in New York.
George W Bush mounted a robust defence of US policies
Mr Bush said democracy was gaining ground in the region and terrorists were being marginalised.
The meeting was opened by UN Secretary General Kofi Annan, who made an urgent plea for peace in the Middle East.
Mr Annan also raised the Darfur crisis in Western Sudan, which he described as the UN's biggest challenge.
In his address, he said ongoing violence there "makes a mockery of our claim to shield people from abusers".
BBC diplomatic correspondent Jonathan Marcus says the issue hangs like a dark shadow over this session, raising questions about the UN's effectiveness and relevance.
The Security Council has backed the despatch of a full UN peacekeeping mission to protect civilians, but the Sudanese government has not approved the force.
Mr Bush said that if the Khartoum authorities did not do so quickly, the UN had to act. "Your lives and the United Nation's credibility are at stake," he added, addressing the people of Darfur.
The US president also announced the appointment of a special US envoy to the region.
Darfur is set to be a contentious issue at the meeting
On the Middle East, Mr Bush rejected criticism that his policies were destabilising the region: "This argument rests on a false assumption - that the Middle East was stable to begin with."
He said recent elections showed that democracy was progressing in many countries, including Iraq and Afghanistan.
"A world beyond terror where the extremists are marginalised by the peaceful majority" was within reach, the US president said.
He also highlighted the crisis over Iran's nuclear programme and urged Tehran to "abandon its nuclear weapons ambitions".
Despite US and European efforts, there has been no unanimity in the Security Council on the issue of sanctions against Iran, which has refused to follow UN demands that it suspend the enrichment of uranium.
Chirac meets Bush
While Russia and China have been dubious about sanctions, France broke ranks with its European allies on Monday when President Jacques Chirac said he did not believe suspension of enrichment should be a precondition for new negotiations with Iran.
Mr Chirac, in his own address to the assembly, said "dialogue must prevail" in the standoff.
However the French leader - who met Mr Bush earlier on Tuesday - also urged Tehran to respond to concerns over its nuclear program.
"International legality must prevail over the threats of proliferation of weapons of mass destruction," he said.
Iran says its nuclear programme is entirely peaceful.
Mr Annan's opening speech to the assembly was his last as secretary general. His second five-year term in office ends at the end of the year.
On the Israel-Palestinian conflict, he said: "As long as the Palestinians live under occupation, exposed to daily frustration and humiliation, and as long as Israelis are blown up in buses and in dance halls, so long will passions everywhere be inflamed."