Three journalists from the biggest Finnish daily went on trial in Helsinki on Thursday for allegedly revealing national defense secrets in a newspaper article.

The prosecutor claims that the two Helsingin Sanomat journalists and their former editor revealed classified information in a report published in December 2017.

The report, titled "Finland's Most Secret Place," focused on the activities of the Finnish Intelligence Research Center, a military intelligence agency.

The investigative report revealed the rough location and tasks of an intelligence unit of the defense forces at a time when Parliament was debating whether to expand its powers to monitor private data in digital networks.

According to the prosecutor, the article contained harmful information and  publishing it was against the law. She demanded the removal of the online version of the original story from the newspaper's website.

What have the journalists said about the case?

Reporters Tuomo Pietilaina and Laura Halmi and the paper's acting manager at the time, Kalle Silfverberg, have denied wrongdoing.

The trio were not present at the District Court of Helsinki but are scheduled to testify at the end of November.

Kaius Niemi, the editor-in-chief of Helsingin Sanomat, had charges against him in connection with the case dropped for lack of evidence.

"We can show for each published sentence that the information could be found on the internet or in books prior to the publication of our article. Public information cannot be classified," he said.

The case is unprecedented in a country renowned for its press freedom.

Finland has for years been among the top countries in a global press freedom ranking published annually by Reporters Without Borders. But the country slipped to fifth place this year, partly because of the court case.

dh/fb (Reuters, AP)