Ahmadinejad had asked to address the council to defend his country's position on its controversial nuclear programme, but an official in Tehran said he will not travel to New York because his visa would not arrive in time.

"President Ahmadinejad's trip has been made impossible because of the lateness in supplying a visa by the United States," the official told AFP late on Friday.

"Because of this, it is not possible to get the visa to Tehran on time, and the president's trip has therefore become virtually impossible.

"The United States deliberately issued the visas late to prevent the president from going, and they are responsible. Also the visas for the team members who would have accompanied him were not issued, which makes the trip impossible," the official said.

Foreign ministry spokesman Mohammad Ali Hosseini accused Washington of "deliberate and conscious negligence."

"The delays in granting the visas were planned in such a way that the trip, given the particularly long distance involved, could not take place," he said.

Foreign Minister Manouchehr Mottaki, who is already in New York, will speak in the president's place, a ministry spokesman said.

Washington denied any visa delays.

"We provided visas to President Ahmadinejad's delegation, including his security and aircrew, in time for him to come to New York and speak at the Security Council on Saturday," said State Department deputy spokesman Tom Casey.

"Any suggestion that visa issues are the cause of President Ahmadinejad's decision not to travel to New York is false."

Casey also said Washington's UN mission "has been informed that President Ahmadinejad has now decided not to come to New York."

State Department spokesman Sean McCormack said an initial 39 visas -- 13 for diplomats and 26 for security staff -- had been delivered in Bern. He said requests for another 33 visas for Iranian crew were still being examined.

"It was one of these incidents when they failed to fill out all the forms. But our folks in Bern are working as quickly as they can to make sure that those visas get issued within the confines of our host country obligations," he said.

Iran and the United States have not held diplomatic ties for the past 27 years, and Switzerland takes care of US interests in Iran.

Ahmadinejad had said he wanted to present what he called "new proposals" about Tehran's nuclear programme.

Defying UN demands, Iran has refused to suspend its uranium enrichment work and rejected accusations that it is striving to produce nuclear weapons, insisting its programme is designed solely to generate electricity.

The new resolution would ban Tehran from exporting arms, calls for voluntary trade sanctions and expands a list of officials and companies targeted for financial and travel restrictions.

It builds on sanctions already adopted by the Security Council in December, including a ban on the sale of nuclear and ballistic missile-related materials to Iran and a freeze on financial assets of Iranians involved in illicit atomic and ballistic missile work.

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