Washington has been pressing Russia to join the West in rebuking Iran at the United Nations but days of haggling to agree on a language for a U.N. Security Council statement against Iran have failed.

Russia has put up the toughest resistance among major powers to the U.S. push for the United Nations to tell Iran to suspend uranium enrichment activity that could produce fuel for an atomic bomb.

The five permanent council members with veto power -- United States, Britain, France, Russia and China -- are all established nuclear powers.

Britain and France drew up the draft statement, backed by the United States. China supports Russia, although diplomats said it has shown more flexibility.

Russia and China fear that involvement by the 15-member council, which can impose sanctions, could escalate and lead to punitive measures, and even justify military action, although the draft statement carries no threat of punishment.

A firm Iran has maintained its programmes are to generate electricity.

Mashaee said Tehran is not concerned about the United Nations but added his country's efforts at building confidence in the international community would continue.

"On the question whether the Republic of Iran will go back on the issue, on the nuclear energy issue, this is not possible at all," Mashaee told a news conference in New Delhi.

"Regarding the international community we will continue our efforts to build confidence with the international community as we have done in the past," he added.

Mashaee is on a rare visit to New Delhi during which he has held talks with Prime Minister Manmohan Singh on energy ties though relations between the long-time allies have been strained over Tehran's controversial nuclear programme.

Relations between New Delhi and Tehran have come under strain after old ally India surprised Iran by siding with the West over the Islamic state's nuclear programme.

But Mashaee denied any heartburn saying New Delhi's approach was fair and in no way anti-Iran.

"I believe that the relations of India with any other country is a domestic affair of India. As the Prime Minister (Manmohan Singh) said India is for a peaceful solution of Iran's nuclear issue and I feel that it is an optimistic move," he said.

Iran is seen as an important ally for India particularly when it comes to surging energy needs in Asia's third-largest economy.

The two nations, along with Pakistan, have been trying to agree on a seven billion dollar project to deliver gas from Iran to energy-deficient South Asia for more than a decade.

But progress has been slow due to India and Pakistan's history of hostility, and more recently because of concerns over Iran's nuclear programme. (ANI)