Six major UN powers were on Monday to resume informal talks on proposed sanctions against Tehran for refusing to suspend nuclear fuel work as Israel warned anew it would not accept a nuclear Iran.
Envoys from Germany and the UN Security Council's permanent members -- Britain, China, France, Russia and the United States -- were to meet at France's UN mission in New York around 3 p.m. (2000 GMT) to review a European draft resolution urging nuclear and ballistic missile-related sanctions against Iran.
The six have already held several exploratory meetings on the sanctions, which include travel bans and financial restrictions on Iranian scientists working on the nuclear and missile programs.
But diplomats said the hard bargaining had yet to begin to find common ground on a text that could then be submitted to the full 15-member Security Council for approval.
The draft put forward by Britain, France and Germany is viewed as too tough and counter-productive by Russia and China, which both maintain close energy and trade ties with Tehran.
The Russians have offered amendments that would drastically reduce the
scope of the sanctions while the US side is pushing for even tougher sanctions.
Monday's informal six-way talks coincided with a new warning from Israeli Prime Minister Ehud Olmert that his country would not accept a nuclear Iran.
Olmert, in Washington for talks with US President George W. Bush, told NBC television's "Today Show" program: "We will not tolerate the possession of nuclear weapons by Iran."
On Sunday, an Iranian foreign ministry spokesman, Mohammad Ali Hosseini, served notice that Tehran would deliver a "destructive" response to any Israeli military attack on its atomic sites and that it would continue trying to boost its capacity for uranium enrichment.
Israel -- widely considered the Middle East's sole, if undeclared, nuclear weapons power -- views Iran as its chief enemy, pointing to calls from President Mahmoud Ahmadinejad for the Jewish state to be wiped off the map.
Meanwhile the White House rebuffed growing calls to hold direct talks with Iran, insisting that Tehran must first suspend uranium enrichment, a process that can lead to the production of fissile material for nuclear weapons.
Monday's meeting also follows top Iranian nuclear negotiator Ali Larijani's two days of nuclear-related talks with Russian leaders in Moscow last week.
After Larijani's talks with President Vladimir Putin on Saturday, Russian Foreign Minister Sergei Lavrov said Iran would continue to study a package of economic and security incentives offered by the six powers if Tehran agrees to halt uranium enrichment.
"Iran has responded to these proposals and we think that in showing its good will, there is a possibility, beginning with the proposals of the six and taking Iran's response into account, to find an acceptable basis for talks to restart," Lavrov said.
"In the days ahead, we will continue our contacts with the six, which have proposed to Iran ideas which serve as the basis for the beginning of negotiations," Interfax quoted the Russian minister as saying.
In a related development, Tehran has asked the International Atomic Energy Agency (IAEA) for technical aid in building a heavy-water nuclear research reactor at Arak about 200 kilometres (120 miles) south of Tehran, according to a Western diplomat who spoke on condition of anonymity.
The request will first be considered next week by the UN agency's technical assistance committee before a meeting of the IAEA's governing board in Vienna on November 23-24, another diplomatic source said.
Western countries suspects Iran is covertly seeking to build nuclear weapons.
Tehran has spurned an August 31 Security Council deadline to halt its uranium enrichment program and insists its nuclear program is peaceful and only aimed at producing electricity.