American and Iranian flags
American and Iranian flagsiStock

The Iranian judiciary on Sunday upheld 10-year jail terms for an American, two U.S.-Iranian dual nationals and a Lebanese permanent resident of the United States for "collaborating" with Washington, AFP reports.

The Tehran prosecutor's office said the four men's appeals had been rejected, according to the news agency.

Xiyue Wang, a Chinese-born American, was sentenced to 10 years in jail for "collaborating with foreign governments", said Tehran prosecutor Abbas Jafari Dolatabadi.

He said the same sentence was upheld against two dual nationals for "collaborating with a foreign government", and Lebanese national Nizar Zakka, a U.S. permanent resident, for working with the American government.

The dual nationals, businessman Siamak Namazi and his father Mohammad Bagher Namazi, were convicted in October 2016 along with Zakka and three others on charges of "spying" for Washington.

The State Department in July called on Iran to immediately release U.S citizens and other foreigners detained on "fabricated" national security charges.

President Donald Trump recently warned of "new and serious consequences" unless U.S. nationals held in the Islamic Republic were released, triggering criticism from Tehran of the detention of Iranian citizens in the United States.

Iran's Foreign Minister Mohammad Javad Zarif has accused Washington of holding Iranians on "charges of sanction violations that are not applicable today... for bogus and purely political reasons", according to AFP.

The State Department, for its part, says Iran continues "to harass, arrest, and detain U.S. citizens, in particular dual nationals", warning that Washington's ability to assist is "extremely limited".

Iran’s move comes amid continued tensions between Washington and Tehran. Iran signed a nuclear agreement with the U.S. five other world powers in 2015, but Trump has been a vocal critic of the Iran nuclear deal, which was signed during the term of the Obama administration.

Trump has described the agreement it as “the worst deal I’ve ever seen negotiated” and threatened to annul it.

While Trump's administration recently confirmed that Iran is adhering to the nuclear agreement it signed with world powers in 2015, Trump and other officials in the administration have stressed that the President still has reservations about the deal.

Iranian officials have downplayed Trump’s threats to tear up the nuclear deal. The head of Iran’s Atomic Energy Organization said last week his country can resume high-level uranium enrichment within five days if the United States tears up the agreement.

The U.S. continues to maintain sanctions on Iran that are related to its ballistic missile tests. Iranian President Hassan Rouhani recently threatened that Iran would walk out on the nuclear deal if the United States continued to apply fresh sanctions.