Reporters Without Borders (RSF) says it is "alarmed about threats" to Iranian journalists based outside of the country who are working for Iranian-exile media outlets or the Persian-language services of international broadcasters.

In an open letter released on January 22, the Paris-based press-freedom watchdog urged the leaders of the host countries -- Britain, France, Germany, the Netherlands, Czech Republic, Sweden, and the United States -- to "explicitly condemn" such threats and to "provide threatened journalists with physical protection."

The leaders should also "intercede directly with the Iranian government to defend the fundamental right to news and information," the letter said.

Iran's media, which is closely controlled by the government control, has "refrained from covering major domestic events," including the anti-government protests that erupted across the country in mid-November, according to RSF.

In an effort to silence the only independent news sources for many Iranians, the government has "stepped up its threats" against Iranian journalists abroad who are working for the Persian-language services of the BBC, Voice of America, Radio Free Europe/Radio Liberty, Deutsche Welle, Radio France Internationale, and Radio Zamaneh, it said.

According to RSF, journalists working for privately owned Iranian-exile media such as the Iran international and Manoto TV channels and the Kayhan London and IranWire news websites have also been targeted.

The threats against Iranian reporters abroad have taken the form of cyberattacks, insults, and intimidation on social media, the watchdog said, adding that journalists working for London-based media have been threatened with "abduction on the street and forced return to Iran."

According to RSF, around 200 Iranian journalists living outside Iran -- mainly in Europe and the United States -- have received harassing messages, of which around 50 have been death threats.

The Iranian authorities have also harassed the journalists' close relatives still in Iran, who are called in for questioning by intelligence officers, it said.