Iran confirmed on Wednesday it had arrested an American, confirming USA media reports about a case that risks further worsening relations with Washington.
The New York Times has quoted White's mother, Joanne, as saying she learned three weeks ago that her son was being held at an Iranian prison.
"His arrest was communicated early through Interests Section of The Islamic Republic of Iran to the United States government".
Mr White, who has acute asthma and has been treated for a tumour in his neck, has been to Iran to see his girlfriend five or six times, she added.
Iranian officials said Mr White was detained in the city of Mashhad, in the north-east of the country.More news: SABC to continue playing R Kelly's music, for now
She is anxious about her 46-year-old son's health because he has had cancer and suffers from asthma, she said.
"Due to privacy considerations, we have no additional information to provide at this time", the representative said.
She said the State Department had not contacted her and she was unaware he was in prison until reached by CNN.
"We have no higher priority than the safety and security of USA citizens overseas".
In July 2017, Iran said that it had detained Chinese-American, Xiyue Wang, a Princeton graduate student who was conducting research in Iran.
Since October 2015, it has also been holding Iranian-American Siamak Namazi.More news: Prince Harry and Meghan Markle's Cotswold country weekender has been revealed
White is the fourth American known to be held by Iran, according to CBS News.
Baquer Namazi, a retired UNICEF official, and his son Siamak, an Iranian-American businessman, were sentenced in 2016 to 10 years in prison for spying and cooperating with the US government.
At least three more USA citizens are being held in Iran, in addition to White.
Another US man has been missing in Iran for over a decade.
In January 2016, Iran freed four USA prisoners - Washington Post journalist Jason Rezaian, Marine veteran Amir Hekmati, Christian pastor Saeed Abedini and Nosratollah Khosravi-Roodsari - in exchange for the U.S. granting clemency to seven Iranians indicted or imprisoned in the United States.
Relations between Iran and the United States deteriorated sharply a year ago when President Donald Trump withdrew from an global accord on Iran's nuclear programme and re-imposed sweeping sanctions.More news: Kate Middleton felt Meghan Markle ‘used’ her to ‘climb the royal ladder’
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