US President George W Bush has strongly defended his decision to invade Iraq and has called on the United Nations to "do more" to help rebuild the country.
Bush called for more UN help in Iraq
Speaking at the UN General Assembly in New York, Mr Bush urged members to support Iraq's interim government.
He said every nation that seeks peace had an obligation to tackle oppression and violence.
"There is no safe isolation from terror networks or failed states that shelter them," Mr Bush said.
Mr Bush was speaking some hours before reports emerged that Iraqi militants had killed a second American hostage.
"We all have a stake in the world's newest democracies," President Bush said, saying the people of Iraq and Afghanistan were on the path to freedom.
He said the decision to invade Iraq was justified, and he challenged UN members to back the government of Iraq's interim Prime Minister Iyad Allawi.
Mr Allawi had "earned the support of every nation that believes in self-determination and desires peace", said Mr Bush.
The issue of Iraq has come back to the fore in the US election race, after Mr Bush's Democratic challenger, John Kerry, on Monday criticised what he called the president's "colossal failures of judgement".
With the poll only six weeks away, Mr Bush took the opportunity to play the statesman and challenge the accusations that his foreign policy has been one-sided and blinkered, reports the BBC's diplomatic correspondent Jonathan Marcus.
Mr Bush highlighted what he called the battle between democratic nations and terrorism.
Recalling the case of a mother whose daughter was killed in the Beslan school tragedy, President Bush said the US was determined to help destroy terrorist networks wherever they operate.
But he also spoke of a better world beyond the war on terror, outlining the need to improve healthcare, expand prosperity and extend freedom as an alternative to terrorism and violence.
He also proposed establishing a democracy fund within the UN to help states foster the rule of law.
The rule of law was the main theme of UN Secretary General Kofi Annan's opening speech, in which he stressed that all states, "strong and weak, big and small", needed a framework of fair rules.
"It is the law, including Security Council resolutions, which offers the best foundation for resolving prolonged conflicts - in the Middle East, in Iraq and around the world," said Mr Annan.
Watching from afar, Iraqis hear Mr Bush pledge to stand by them
Civilians were being massacred in cold blood in Iraq while relief workers, journalists and other non-combatants were taken hostage and killed in the most barbarous fashion, he said.
"At the same time, we have seen Iraqi prisoners disgracefully
abused," he said, a reference to the Abu Ghraib prison scandal in Iraq.
Mr Annan's speech was a strong rebuke to the stronger nations, in particular the US, correspondents say.
President Bush was among the first to address the two-week debate of the 191 member countries.
Speaking to reporters in New York, the president rejected Mr Kerry's accusations that his mistakes had led to a huge crisis in Iraq.
"My opponent has taken so many different positions on Iraq that his statements are hardly credible at all," Mr Bush said.
For his part, Mr Kerry said Mr Bush had failed to present a true picture of Iraq to the UN and "does not have the credibility to lead the world".