A prominent investigative reporter in Azerbaijan on trial for libel was barred from leaving the country Oct. 11 as she tried to fly to the Czech Republic to attend a media conference.

Khadija Ismayilova is well-known for her reporting on the business interests of President Ilham Aliyev’s family. She is currently facing criminal defamation charges for reporting on an alleged attempt by the Azeri security services to use an illegally filmed sex tape to blackmail an opposition activist into informing on other opposition figures, Radio Free Europe/Radio Liberty reported.

In 2012 and 2013, Ismayilova was the target of a similar campaign during her investigation of the Aliyev families businesses. Intimate photos and video of her in her apartment surfaced on state media and pro-government websites, according to the Washington Post.

On Oct. 16, 12 press freedom and human rights groups called for Ismayilova’s travel ban to be ended. “Khadija Ismayilova is one of the most recognized investigation journalists in Azerbaijan,” said Virginie Dangles, a deputy program director with Reporters Without Borders, in a statement.  “Harassing her is sending a clear signal of intimidation to the entire media profession.”

Ismayilova is the recipient of both the 2012 Gerd Bucerius Free Press of Eastern Europe Award and the 2012 Courage in Journalism Award from the International Women’s Media Foundation.