WASHINGTON (AP) — Iranian President Hasan Rouhani said Wednesday that his country has never sought and will never seek a nuclear bomb, telling NBC News in an interview that he has full authority to resolve a standoff with the West.

Rouhani spoke to the American television network in Tehran just days before he is to make his first appearance as president on the world stage when he attends the United Nations General Assembly in New York. U.S. officials will be watching next week's visit closely for signs that Rouhani will warm relations with the West and take a more moderate line in the next negotiations on Iran's disputed nuclear program.

"We have never pursued or sought a nuclear bomb and we are not going to do so," Rouhani said, according to an NBC translation of the interview. "We have time and again said that under no circumstances would we seek any weapons of mass destruction, including nuclear weapons, nor will we ever."

It was a claim Iran has made before, that its nuclear activities are purely peaceful. However, the U.S. and its allies suspect Iran is trying to develop a nuclear weapon, a feat some experts say the country might be able to accomplish as early as next year.

Rouhani also addressed a question that many in the U.S. have been asking: Does he really have the power to make major decisions and concessions on the nuclear issue?

Iranian Supreme Leader Ayatollah Ali Khamenei is known to control all important matters of state, including nuclear.

"In its nuclear program, this government enters with full power and has complete authority," Rouhani said. "We have sufficient political latitude to solve this problem."

Rouhani is considered a relative moderate in Iran's hard-line clerical regime. He campaigned on a promise to seek relief from punishing U.S. and Western sanctions that have slashed Iran's vital oil exports by more than half in the past two years, sent inflation soaring and severely undercut the value of its currency.

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Turning to the Syria, Rouhani addressed U.S. allegations that the Iranian-allied regime was behind a chemical weapons attack near Damascus last month. He said his country seeks peace and stability and the elimination of weapons of mass destruction in the entire region.

Asked whether President Barack Obama had looked weak by backing off a military strike on the Syrian regime, Rouhani responded: "We consider war a weakness. Any government that decides on war, we consider a weakness. And any government that decides on peace, we look on it with respect for peace."

Rouhani also said he received a "positive and constructive" letter from Obama congratulating him on his election in June. In it, he said Obama raised some issues the U.S. president was concerned about and that he had responded to the points Obama raised.

"From my point of view, the tone of the letter was positive and constructive," Rouhani said. "It could be subtle and tiny steps for a very important future."

White House spokesman Jay Carney said Wednesday there were no current plans for Obama to meet Rouhani at the U.N. General Assembly.

"I think it's fair to say that the president believes there is an opportunity for diplomacy when it comes to the issues that have presented challenges to the United States and our allies with regards to Iran," he said. "And we hope that the Iranian government takes advantage of this opportunity."

Carney said the U.S. will test Rouhani's assertions that he wants to improve relations with the international community.

He also noted that Obama had confirmed the exchange of letters with Rouhani. In his letter, Obama indicated that the U.S. was ready to resolve the nuclear issue in a way that would allow Iran to demonstrate that its program was exclusively for peaceful purposes, Carney said.

"The letter also conveyed the need to act with a sense of urgency to address this issue because as we have long said, the window of opportunity for resolving this diplomatically is open, but it will not remain open indefinitely," Carney said.

NBC said more details and excerpts from the interview will be published and aired later Wednesday and Thursday morning.