Trump has urged Iran to release former FBI agent Robert Levinson, who has been missing since 2007, saying it would be a "positive step".

"If Iran can return to the abducted former FBI agent Robert A. Levinson, who has been missing in Iran for 12 years, it will be a very positive step," US President Donald Trump posted on Twitter 10/11.

Robert (Bob) Levinson, former agent of the US Federal Bureau of Investigation (FBI), disappeared mysteriously in March 2007 during a visit to Kish Island in Iran. In late 2013, US media reported that Levinson was paid by the Central Intelligence Agency (CIA) to collect information during visits to Iran.

Since his disappearance, photos and videos of Levinson in orange-like prison clothes and shackles have appeared on social media in 2010 and 2011. The family of former agents is suing Iran in court. The US federal government accused the government of kidnapping him.

Iran had previously acknowledged that the Islamic Revolutionary Court had considered a case involving Levinson, but a Foreign Ministry spokeswoman said on Tuesday it was handling a "missing person" notification. , is not an indication that the former US agent has been indicted by the country.

Secretary of State Mike Pompeo announced last week that the State Department would increase the reward from $ 5 million to $ 20 million for those who have information on former Levinson agents. He asked Iran to release all the missing Americans who are being illegally detained, including Robert Levinson. "We will not stop until they are reunited with the family," Pompeo said.

The United States has asked Iran for more than a decade to provide information about Levinson, but officials in Tehran say they have no information about the former missing agent. Levinson, the father of seven children, has diabetes and high blood pressure, making the family worried that he could be seriously affected by health without proper medical care.