Iran has sentenced a Chinese-born American dual national to 10 years in jail, accusing him of spying for the US government.

Gholam-Hossein Mohseni-Eje’i, spokesman for the Iranian judiciary, said in a weekly press briefing in Tehran on Sunday that a US citizen who was also a national of a second country had been convicted for being “an infiltrating American agent”, according to Mizan Online, a news agency affiliated with the judiciary.

Mohseni-Eje’i did not identify the accused but Mizan later named him as Xiyue Wang, 37, a graduate student in history at Princeton University.

“He had entered the country through a special connection but the ministry of intelligence identified him and arrested him,” the Iranian spokesman said. “It became clear that he was involved in the infiltration project and the initial court has sentenced him to 10 years but this could be appealed.”

Last year, Iran’s supreme leader, Ayatollah Ali Khamenei, warned against “an infiltration” from outside into the country’s political system. Since then, “infliltration” has become a code word for those accused by the authorities of having links with the west.

A string of dual nationals, mostly with additional Iranian nationality, have been accused of being part of the so-called infiltration network. Mohseni-Eje’i said Wang was “directly directed by the US”.

Princeton did not immediately return a request for comment. It was not possible to investigate the allegations against Wang independently. Iran has a history of making such allegations.

In response to reports about Wang, the state department called for the immediate release of all US citizens in jail in Iran.

“The Iranian regime continues to detain US citizens and other foreigners on fabricated national-security related changes,” a press statement said. “The safety and security of US citizens remains a top priority. All US citizens, especially dual nationals considering travel to Iran, should carefully read our latest travel warning.”

In January 2016, Iran released an Iranian-American Washington Post reporter, Jason Rezaian, who had been imprisoned for 18 months on spying charges. Rezaian has since sued the Iranian government, accusing it of hostage-taking and torture.

Mizan said Wang pursued espionage “through the cover of being a researcher”. The accused, the agency said, had been working on a digital archive for “the world’s biggest anti-Iran spying organization”. The allegations were based on an anonymous “informed source”, it said.

“He entered the country under the cover of a master’s student,” the report said, “but has been gathering secret and top secret [information]” for organizations such as “the US state department … the Harvard Kennedy School” and the British Institute of Persian Studies. Wang was accused of infiltrating Iran’s national archive and building a 4,500-page digital archive.

Other American dual nationals are currently held in Iranian jails. Among them is the Iranian-American Baquer Namazi, a former Unicef official sentenced to 10 years alongside his son, Siamak Namazi. United Nations chief António Guterres recently reached out to Iranian president Hassan Rouhani regarding their imprisonment.

Also in jail in Iran is Nizar Zakka, a Lebanese technology expert and US permanent resident held since September 2015 on spying charges. He was also sentenced to 10 years.