(CNN) Iran has freed four U.S. prisoners as part of a prisoner swap, including Washington Post journalist Jason Rezaian, Marine veteran Amir Hekmati and Christian pastor Saeed Abedinir, senior U.S. administration officials said Saturday, confirming reports first published in Iranian media.

A fifth man -- described as a recently detained student named Matthew Trevithick-- was separately released, U.S. officials said.

The announcement comes on a day when the United Nations' nuclear watchdog is expected to announce whether Iran is in compliance with a July deal to restrict its nuclear program.

If the International Atomic Energy Agency certifies that Iran is in compliance, some international economic sanctions against Iran are expected to be lifted.

As part of the deal, Iran agreed to release of Rezaian, Hekmati, Abedinir and a fourth detainee identified by U.S. officials as Nosratollah Khosravi-Roodsari in exchange for the release of seven Iranians held by the United States on sanctions charges, the officials confirmed. The deal comes after more than a year of secret negotiations, the officials said.

The United States also agreed to drop charges against 14 other Iranians whose extradition seemed unlikely, a U.S. official said on background.

In addition, the agreement calls for Iranian officials to "continue cooperating with the United States to determine the whereabouts of Robert Levinson," a U.S. official said on background. Levinson is the former FBI agent and CIA contractor who went missing in Iran in 2007.

Iran has denied holding him.

"We are happy for the other families," Levinson's family said in a statement. "But once again, Bob Levinson has been left behind. We are devastated."

Trevithick's release was not part of the prisoner swap, but U.S. officials did "indicate to Foreign Minister [Javad] Zarif that it'd be important for them to try to resolve some of the other cases of Americans detained in the context of this" deal," a senior administration official told CNN.

The freed Americans had not yet left Iran as of 11:15 a.m. ET Saturday, the officials said.

Rezaian was detained by Iran in 2014 and eventually charged with espionage and other crimes, according to the Washington Post. He was the newspaper's Tehran bureau chief.

The newspaper and the United States have called the charges "absurd." Supporters say he has been denied proper legal representation.

"We couldn't be happier to hear the news that Jason Rezaian has been released from Evin Prison," Washington Post spokeswoman Kris Coriatti said in a statement. "Once we receive more details and can confirm Jason has safely left Iran, we will have more to share."

Rezaian's brother Ali also said he had no immediate confirmation of the news.

Hekmati was detained in 2011, weeks after arriving in Iran to visit his grandmother, according to his family's website. The former Marine infantryman and Arabic and Persian linguist was accused of espionage and other charges in 2012.

He appeared on Iranian television and said he was working for the CIA in a confession her mother and the U.S. State Department has said was forced and fabricated.

He was later sentenced to death.

The punishment was later overturned, but Hekmati was later convicted of "cooperating with hostile governments" and sentenced to 10 years in prison, according to a website set up by his supporters.

During his imprisonment, he has suffered from health problems, including weight loss and breathing difficulties, according to his family.

His family released a statement thanking supporters for standing with the family since his arrest.

"There are still many unknowns. At this point, we are hoping and praying for Amir's long-awaited return," the statement read.

Abedini, an Iran native and convert to Christinanity, was arrested in 2012 and convicted the next year on charges of attempting to undermine the Iranian government. He had been sentenced to eight years in prison.

His arrest came three years after he had been arrested by Iranian authorities and later released after agreeing to stop organizing churches in homes. His 2012 arrest came during a trip to help build a state-run secular orphanage.

The American Center for Law and Justice, a Washington-based group dedicated to protecting religious and constitutional freedoms, reported that Abedini has endured torture during his imprisonment and was beaten by fellow prisoners in June. He suffered injuries to his face during that incident, the center reported.

"We're delighted this day has finally arrived," ACLJ Chief Counsel Jay Sekulow said in a statement. "Pastor Saeed should never been imprisoned in the first place."

Abedini's wife, Naghmeh Abedini, said in the statement that the release was "an answer to prayer."