A dual Iranian-American national says he has been sentenced to 18 years in prison in Iran for allegedly collaborating with a hostile government.
Robin Shahini told Vice News in a telephone interview that he had "just laughed" after hearing the sentence.
The 46-year-old graduate student from in San Diego was held in July while visiting his sick mother in Iran.
Iranian judiciary officials have so far not confirmed the sentence.
Last week, two other Iranian-Americans were convicted on similar charges.
Siamak Namazi, a Dubai-based businessman, and his 80-year-old father Baquer were given 10-year jail terms.
A British-Iranian charity worker, Nazanin Zaghari-Ratcliffe, was imprisoned on secret charges last month.
In the interview with Vice News from prison, Mr Shahini said his arrest by Revolutionary Guards personnel in Gorgan, about 300km (185 miles) north-east of Tehran, on 11 July was a "terrifying moment".
"They blindfolded me and they took me to the custody and I did not know where I was," he said. "They were interrogating me every morning, every afternoon, and I was always by myself in my cell."
Mr Shahini, who emigrated to the US in 2000, denied collaborating with a hostile government, but admitted supporting the mass protests that broke out in Iran in 2009 after the disputed re-election of then President Mahmoud Ahmadinejad.
"Whatever information they had is all the pictures I posted in Facebook, in my web blog, and they use all those evidence to accuse me," he said.
His trial took place last week, and he was convicted on Saturday after a three-hour court proceeding, the Los Angeles Times quoted him as saying on Tuesday.
Mr Shahini said he planned to go on hunger strike until he was released.
The US state department said it was "troubled" by the reported sentence.
"We reaffirm our calls on Iran to respect and protect human rights and fundamental freedoms, cease arbitrary and politically motivated detentions and ensure fair and transparent judicial proceedings," it told the Associated Press news agency.
A number of Iranians with dual US, British and Canadian citizenship have been imprisoned since a nuclear deal agreed with world powers took effect in January.
The accord has yet to yield significant economic benefits for Iran, and hardliners are reportedly determined not to let it lead to greater rapprochement with the US.