UNITED NATIONS (AP) -- U.N. human rights experts on Friday called on Iran to immediately release a Washington Post reporter who has been detained for more than a year on charges including espionage and distributing propaganda against the Islamic Republic. A verdict on Jason Rezaian's case could come as early as next week.

The statement says the detention and closed-door trial violate the Iranian-American reporter's rights and serve to intimidate other journalists in Iran. It says his solitary confinement and full-day interrogation sessions "caused significant physical and psychological strain."

The statement was issued by the special rapporteurs for freedom of expression and for human rights in Iran and by the head of the working group on arbitrary detention.

Washington Post Executive Editor Martin Baron said the statement "comes at a critical moment" and upholds the newspaper's stance that Iran's conduct in the case has been illegal. He called the trial a "sham."

Both the newspaper and Rezaian's family have said they believe the reporter is a victim of the hostility between Iran and the United States that dates back to the 1979 Islamic Revolution.

Iranian officials insist the judiciary is independent and say no one is authorized to intervene in judges' decisions.

Rezaian, 39, was detained on July 22, 2014, in Tehran along with his wife, Yeganeh Salehi, and two photojournalists. All were later released except Rezaian, who according to the Post faces up to 10 to 20 years in prison if convicted.

Rezaian was born and spent most of his life in the United States, and holds American and Iranian citizenship. Iran does not recognize dual nationalities for its citizens.

The case has played out as Iran negotiated with the U.S. and other world powers to reach a landmark deal that gives the Islamic Republic relief from sanctions in exchange for curbs on its nuclear program aimed at preventing it from building an atomic bomb. The Obama administration is now trying to secure congressional support for the deal.

U.S. officials have pressed for the release of Rezaian and other Americans detained in Iran, and Washington has joined Rezaian's family and media freedom groups in criticizing the charges against him.

By AP