The BBC has filed a complaint with the United Nations over Iran freezing the assets of more than 150 people associated with its Persian service, calling the Islamic republic's actions "a deprivation of human rights."
The British broadcaster said on October 25 that Iran's move was part of a "criminal investigation" into the BBC's staff, former employees, and contributors over allegations they fomented a "conspiracy against national security" in Iran.
Those swept up in the investigation include Iranian dual nationals from Australia, Austria, Canada, France, Germany, Britain, and the United States, the BBC said.
"This is the latest in a sustained campaign of harassment and persecution which is designed to pressure journalists against continuing their work for the BBC," the broadcaster said.
Iran's mission at the UN did not respond to requests for comment.
The BBC first disclosed the asset freezes in August, saying they came from a court at Tehran's notorious Evin prison, which holds dual nationals and political detainees, among other prisoners.
The court order stopped those named from selling, buying, or inheriting property and assets in the country until December 20, when the outcome of the criminal investigation is to be announced, according to the complaint.
"BBC Persian staff are unable to return to Iran as they risk arrest, interrogation, and imprisonment," the complaint said. "Many BBC Persian staff have been separated from their families for years and, in a number of cases, were unable to see loved ones before they have died."
The BBC's complaint was sent to David Kaye, the UN's independent investigator on freedom of expression. He told journalists at UN headquarters in New York that he had received the BBC's complaint.
"We raised very serious concerns with the government just over the last couple of days," he said.
"We urge the government of Iran to stop harassing the employees and families of employees of the BBC Persian service as well as other journalists," he said.
"It's a very, very serious concern to us, in part because it's reflective of an overall pattern, but also because it's creating direct harm against individuals who are only trying to do their job, which is a job that is protected by international human rights law."
The BBC's Persian-language service was barred from operating in Iran after Tehran's disputed 2009 presidential election.
But the broadcaster's complaint said many Iranians listen to its radio shows and watch its satellite television broadcasts, despite "the Iranian government repeatedly jamming BBC Persian TV." The BBC said its service reaches some 18 million people weekly.
BBC staffers and their families have been targeted by Iran's government in the past, especially by hard-liners within the judiciary and security services. Others have been the target of online harassment and "malicious and defamatory fake news stories" in Iranian state media, the complaint said.
A former BBC World Service Trust employee named Nazanin Zaghari-Ratcliffe is serving a five-year prison sentence over allegations of planning the "soft toppling" of Iran's government while traveling there with her toddler daughter.
Zaghari-Ratcliffe, a British-Iranian woman, now works for the Thomson Reuters Foundation, the charitable arm of the news agency. She's been threatened recently with charges that could add another 16 years to her prison sentence.