ISTANBUL — In leaked audio recordings made public Sunday, Iran's foreign minister complained about interference by the Revolutionary Guard Corps in Tehran's diplomatic affairs, including efforts to undermine the 2015 nuclear deal between Iran and world powers.

The audio, which was released by the London-based Iran International news channel, came from a lengthy interview with the foreign minister, Mohammad Javad Zarif, that the channel said was conducted in March. Zarif’s unvarnished comments —and the unexplained leak of the audio — highlighted the sharpening public rivalries within Iran’s political circles, as Tehran engages with global powers in a fresh attempt to revive the nuclear deal, and as Iranian elections approach.

Especially notable were Zarif’s barbed comments about Maj. Gen. Qasem Soleimani, the commander of the Guard’s elite Quds Force, a towering figure in Iran’s security establishment who was killed in a U.S. drone strike last year. Zarif said Soleimani had worked to subvert the nuclear deal, by colluding with Russia and by ramping up Iran’s intervention in Syria’s civil war.

“Almost every time I went to negotiate, it was Soleimani who said, ‘I want you to make this concession or point,’ ” Zarif said. “I was negotiating for the success of the [military] field.”

The interview was conducted by Saeed Leylaz, an economist and journalist who was an adviser to Mohammad Khatami, a pro-reform cleric who served two terms as Iran’s president. In the excerpts published by Iran International, Zarif can he heard asking Leylaz not to publish certain parts of the conversation. The channel said the interview was apparently intended to be released after Iran’s current president, Hassan Rouhani, left office in August.

On Monday, Saeed Khatibzadeh, an Iranian Foreign Ministry spokesman, called the leak “illegal” and said the conversation was intended only for “historical” purposes, adding that there had been “a mutual commitment to maintaining its confidentiality,” according to the semiofficial Iranian Students’ News Agency.

He said the government did not know who had leaked the audio, or why, but said the conversation also showed that “Iranian officials are dynamic and transparent in their expertise.”

A version of the audio posted on Iranian Telegram channel ran slightly more than three hours. Khatibzadeh said the entire conversation lasted seven hours, according to ISNA.

The leaked conversation was the latest salvo in what has become an increasingly caustic domestic Iranian debate over the nuclear deal, pitting “pragmatists” represented by Rouhani against a conservative camp wary of any engagement with the West. The factional fights are not a secret in Iran, which hosts political debates that are more expansive and vigorous than most countries in the Middle East.

Even so, Zarif’s comments, some of which could be seen as self-serving, were notably blunt. “The general structure of our Foreign Ministry is security-based,” he said. “There is a group in our country that has an interest in making everything security-based, to highlight their own role.”

Despite his apparent frustration with Iran’s security apparatus, Zarif also spoke warmly of Soleimani in the recording, saying at one point that the military officer, who commanded Iranian proxy forces around the Middle East, “did not seek war. This is one reason I loved him so much.”

Iran’s debate has intensified in the past few weeks as the Rouhani government, the United States and other global powers meet in Vienna to revive the nuclear deal, which languished after President Donald Trump withdrew from the accord in 2018.

In Iran, the argument has played out on the Internet and the airwaves, including with the recent broadcast of a documentary and a television series that were widely seen as attempts by hard-liners to undermine the nuclear talks.

The quarrels in Iran revolve to some degree around the terms of the deal, analysts said, but more importantly amount to jockeying between factions ahead of presidential elections scheduled for late June.

In the interview, Zarif addressed speculation about his own candidacy, saying he was “popular,” while adding: “Popularity is not a legitimate reason to be able to run the country.”

“I believe Iran and U.S. are never going to have normal relations,” Zarif said, according to the audio. “We are never going to be able to resolve all our disputes.” But “we can have conflict management with the U.S. at least,” he added.