New Iranian President Hassan Rouhani promised that his country will never make nuclear weapons, as part of a larger move toward settling a long-standing rift with the United States over the country's atomic program, NBC News reported on Wednesday.

"Under questioning, he made a categorical statement: He said Iran will 'never develop nuclear weapons under any circumstances, and that he has 'full authority' to make a deal with the West" NBC correspondent Ann Curry told MSNBC host Andrea Mitchell in a telephone interview. "He was, of course, clearly stating that he has the support of Iran's Supreme Leader, Ayatollah Ali Khamenei, who is in charge of Iran's nuclear program."

Curry conducted the first U.S. interview with Rouhani, which NBC said would air Wednesday night. In a preview clip released that afternoon, Rouhani said he had exchanged correspondence with U.S. President Barack Obama shortly after Rouhani's inauguration on Aug. 4.

"In that letter he congratulated my election and some issues of his interest raised in the letter," Rouhani told Curry. "I responded to that letter. I thanked him, and expressed Islamic Republic of Iran's viewpoint on the issues President Obama raised in his letter, and some other issues. From my point of view, the tone of the letter was positive and constructive."

NBC reported that Rouhani's statements run counter to that of the country's foreign ministry, which criticized Obama's letter earlier this week.

"Unfortunately, the U.S. administration is still adopting the language of threat while dealing with Iran," ministry Marzieh Afkham reportedly told the New York Times in an interview published on Tuesday. "We have announced that this needs to change into the language of respect."

Update, 8:14 p.m. EST: NBC aired a longer excerpt from Curry's interview with Rouhani Wednesday night, in which he tells Curry Iran has never tried to build a nuclear weapon. Instead, he explained, "We solely are looking for peaceful nuclear technology."

"Can you say that Iran will not build a nuclear weapon under any circumstances whatsoever?" Curry asked.

"The answer to this question is quite obvious," Rouhani responded. "We have time and against said that under no circumstances would we seek any weapons of mass destruction, including nuclear weapons, nor will we ever."

According to Curry, Rouhani also claimed that Iran was playing "a major role" in finding a diplomatic solution regarding Syria's chemical weapons arsenal, currently the subject of the negotiations between the U.S. and Russia.

"We are one of the countries of this region which is asking peace and stability and the elimination of all weapons of mass destruction in the entire region," Rouhani told Curry.

Watch a portion of Curry's interview with Rouhani, aired Wednesday night, below.

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Watch Mitchell's phone interview with Curry, aired Wednesday on MSNBC, below.

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And watch a clip of Curry's interview with Rouhani, also released on Wednesday, below.

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