Nearly 200 nations, signatories of the Nuclear Non-Proliferation Treaty (NPT), have agreed to work towards a nuclear-weapons-free zone in the Middle East.
The members, meeting at the UN in New York, called for a conference in 2012 attended by Middle Eastern states - including Iran - to establish the zone.
The unanimously agreed document also said that Israel should sign the NPT.
US President Barack Obama backed the deal but said he was "strongly opposed" to Israel being singled out.
The US says the reference could jeopardise efforts to persuade the Israelis to attend the 2012 talks.
An Israel official later denounced the document as "hypocrisy".
"Only Israel is mentioned, while the text is silent about other countries like India, Pakistan and North Korea, which have nuclear arms, or even more seriously, Iran, which is seeking to obtain them," a senior government official told AFP news agency on condition of anonymity.
The 28-page final declaration was agreed by 189 member states following intense talks on the last day of a month-long conference on strengthening the NPT, the cornerstone of global disarmament efforts.
The document calls for the United Nations secretary general to organise a meeting of Middle East states in 2012 to agree to the creation of a "zone free of nuclear weapons and all other weapons of mass destruction".
"All eyes the world over are watching us," said conference president Libran Cabactulan, of the Philippines, as the final text was approved.
Egypt's Maged Abedelaziz, speaking for the Non-Aligned Movement of 118 developing nations, welcomed the decision, saying it was "an important step forward towards the realisation of the goals and objectives of the treaty".
Diplomats discussing the proposals had continued talks late into the night on Thursday before resuming on Friday.
One of the sticking points involved Israel, which is not a member of the NPT, and is widely believed to have nuclear weapons. It has never admitted possessing them.
Arab states and Israel's allies had to work hard to find agreement over wording for the proposed nuclear-weapons-free zone.
Correspondents say Arab nations want to put pressure on Israel to relinquish its undeclared nuclear arsenal.
Iran also made a late demand that the five recognised nuclear-armed nations agree to a timetable for negotiating a treaty to abolish their arsenals.
In the final document adopted, no specific timetable is set out but the five states commit to "accelerate concrete progress" towards reducing their nuclear arsenals and to report back on that in 2014.
Iran has faced repeated questions over its own nuclear programme, which the West believes is aimed at making weapons. Tehran insists it is solely designed to meet its energy needs.
Iran, a member of the NPT, says it will stick to its obligations under the treaty.
The NPT has encountered difficulty in coming up with the best method for monitoring suspect nuclear programmes in Iran and North Korea.
India, Pakistan, North Korea and Israel - which are known or suspected to have nuclear weapons - are not signatories to the treaty. They are not covered by any NPT agreement.
The NPT conference meets every five years. The last review conference, in 2005, failed to adopt a consensus declaration.