A prisoner swap between the United States and Iran was expected to take place on Monday, according to a spokesman for the Iranian Foreign Ministry, after two years of high-stakes negotiations.
As part of the deal, the United States had agreed to unfreeze $6 billion in Iranian oil revenue and dismiss federal charges against several Iranians accused of violating U.S. sanctions.
The announcement at a news conference in Tehran from the spokesman, Nasser Kanaani, came as President Biden and Ebrahim Raisi, Iran’s president, were to attend the annual United Nations General Assembly meeting of world leaders on Tuesday. The spokesman’s remarks were published on the website of the Iranian news agency ISNA.
Mr. Kanaani said five Iranians, several of whom are permanent residents of the United States, were expected to be released. It was not immediately clear exactly how many of the Iranians would return to Iran, although Mr. Kanaani said it would be two.
Five American prisoners some of whom had been held for years in Evin Prison, one of the most notorious detention centers in Iran, were expected to be released as part of the deal.
The Americans — Siamak Namazi, Emad Sharghi and Morad Tahbaz, as well as two others who have not been named at their families’ request — had been jailed on unsubstantiated charges of spying.
They had spent the last several weeks in Iran in home detention after Tehran agreed to release them from prison while the $6 billion transfer, a complicated process, was being completed.
Top aides to Mr. Biden have said financial sanctions will prevent Iran from spending the money on anything except food, medicine and other humanitarian goods. But they acknowledge that the deal might free up money that Iran is already spending on those items for other purposes.
The terms of the deal have generated intense criticism from Republicans, who accused Mr. Biden of helping to finance Iran’s terrorist activities around the world.
Administration officials have said the agreement with Iran was the only way to win the release of the five Americans, who the United States said had been wrongfully detained by the Iranians in deplorable conditions.
The deal was as part of a larger effort by the Biden administration to de-escalate tensions with Iran, which had soared in the years since President Donald J. Trump abandoned the 2015 Iran nuclear deal, which placed limits on Tehran’s nuclear program in exchange for sanctions relief.
In an interview last week in Tehran with Lester Holt, the NBC News anchor, Mr. Raisi said that the American detainees held in Iran were in “good health” and that Tehran had authority over how it used its released funds.
“This money belongs to the Iranian people, the Iranian government, so the Islamic Republic of Iran will decide what to do with this money,” Mr. Raisi said.