Tehran says that Robert Levinson, a former FBI agent, left the country “long ago” and doesn’t know where he is, rejecting a claim by his family saying he died in Iranian custody.

"Based on credible evidence, [Levinson] left Iran years ago for an unknown destination," Foreign Ministry spokesman Abbas Musavi said in a statement on March 26.

He added that officials had done everything possible to find out what happened after Levinson left Iran but had found "no evidence of him being alive."

"Iran has always maintained that its officials have no knowledge of Mr. Levinson's whereabouts, and that he is not in Iranian custody. Those facts have not changed," added Alireza Miryousefi, a spokesman for the Iranian mission at the United Nations.

The Iranian comments come in response to a White House statement saying that the U.S. administration believed Bob Levinson may have passed away "some time ago."

"Iran must provide a complete accounting of what occurred with Bob Levinson before the United States can fully accept what happened in this case," White House national-security adviser Robert O'Brien said in a statement about the American, who disappeared in Iran 13 years ago, when he was 58.

Before that statement, Levinson’s family posted on social media that it had received word about his likely fate from the U.S. government.

"We recently received information from U.S. officials that has led both them and us to conclude that our wonderful husband and father died while in Iranian custody," the Levinson family said in a statement.

"We don’t know when or how he died, only that it was prior to the COVID-19 pandemic," it added.

Following the family's announcement and before O’Brien’s comments, President Donald Trump told reporters that "I won't accept that he's dead."

Levinson had been "sick for a long time" before he was detained, Trump said, adding that he felt "terribly" for the family but still had some hope that Levinson was alive.

"It’s not looking great, but I won’t accept that he’' dead. They haven't told us that he's dead, but a lot of people are thinking that that’s the case," he said.

Levinson disappeared when he traveled to the Iranian resort of Kish Island in March 2007. He was working for the CIA as a contractor at the time.

The United States has repeatedly called on Iran to help locate Levinson and bring him home, but Iranian officials said they had no information about his fate.

However, when he disappeared, an Iranian government-linked media outlet broadcast a story saying he was "in the hands of Iranian security forces."

The Levinson family said he would be alive today “if not for the cruel, heartless actions of the Iranian regime."

"How those responsible in Iran could do this to a human being, while repeatedly lying to the world all this time, is incomprehensible to us. They kidnapped a foreign citizen and denied him any basic human rights, and his blood is on their hands,” the statement added.

With reporting by AP, Reuters, and AFP