Iran has rejected demands by the United States that Tehran release Americans detained in Iranian prisons.
Iranian Foreign Ministry spokesman Bahram Qassemi said in a statement on July 22 that "any interventionist and threatening statement by American officials and institutions has no effect on the will and determination of the country's judicial system to try and punish criminals and violators of the country's laws and national security."
The comment came one day after U.S. President Donald Trump warned that Iran faces "new and serious consequences" unless all "unjustly detained" American citizens are released and returned.
Trump urged Iran to return Robert Levinson, a former FBI agent who disappeared more than 10 years ago in Iran, businessman Siamak Namazi and his father Baquer, and "all other American citizens unjustly detained by Iran."
"For nearly forty years, Iran has used detentions and hostage taking as a tool of state policy, a practice that continues to this day with the recent sentencing of Xiyue Wang to ten years in prison," the White House said, referring to a Princeton University researcher who was sentenced by Iran for spying last week.
But Qassemi said Iran's "judiciary, courts, and judges are completely independent" and he added that Tehran has no "new information" about Levinson, who he claims left Iran.
"America should quickly release Iranian prisoners in the country," said Qassemi, claiming that several Iranians have been jailed in the United States in recent years on "baseless and unfounded grounds."
The White House statement on July 21 continued by saying that "Iran is responsible for the care and well-being of every United States citizen in its custody."
"President Trump is prepared to impose new and serious consequences on Iran unless all unjustly imprisoned American citizens are released and returned."
The warning to Iran came as the White House said it is "redoubling efforts" to bring back all Americans unjustly detained overseas.
Levinson, the former FBI agent, disappeared on a visit to Iran's Kish Island in 2007.The U.S. government has a $5 million reward for information leading to his safe return.
His children told CNN in March that they felt confident Trump would be able to bring their father home.
Tehran has denied having anything to do with his disappearance and has said it doesn't know where he is.
An Iranian court sentenced each of the Namazis last year to 10 years in prison on charges of spying and cooperating with the United States. Family members have expressed concerns about the health of the elder Namazi, Baquer, 80, a retired UNICEF official.
His son Siamak, a businessman, was detained in October 2015 while he was visiting family in Tehran.
Both of the Namazis are dual Iranian-American citizens, but Iran does not recognize dual citizenship and considers all Iranian nationals to be solely Iranian citizens.
That has resulted over the years in the imprisonment of numerous dual nationals upon their return to Iran.
Another dual Iranian-American, Robin Shahini, was detained as he was visiting relatives in Iran last year and later sentenced to 18 years in prison for alleged spying.
His shocked family said all the evidence in the graduate student's three-hour trial was based on Facebook and blog posts supporting the 2009 election protests in Iran.
Iranian authorities announced last week that a court had sentenced Xiyue Wang, a Chinese-born U.S. citizen and Princeton graduate student, to 10 years in jail on spying charges.
Xiyue was arrested nearly a year ago but his case became public only last week after Iran’s judiciary announced his sentence. He was accused of "infiltrating" the country and sending confidential material abroad.
Xiyue was in Iran doing research for his doctorate in late 19th and early 20th century Eurasian history when he was detained.
His wife told The Washington Post that her husband is innocent. She said he was in Iran to learn Persian and do scholarly research.
With reporting by Reuters and AFP