BRATISLAVA (Reuters) - Slovakian authorities said on Wednesday they have taken the cell phone of a colleague of a journalist whose murder in February sparked mass protests that forced the government to resign.

A man attends a protest rally in reaction to the murder of Slovak investigative reporter Jan Kuciak and his fiancee Martina Kusnirova, in Bratislava, Slovakia April 5, 2018. REUTERS/Radovan Stoklasa

Journalist groups on Wednesday condemned what they said was the police confiscation of Czech reporter Pavla Holcova’s phone.

Holcova said in February she may have been one of the last people to talk by phone to Slovak investigative journalist Jan Kuciak before he and his fiancée, both 27, were shot dead in their home outside Bratislava.

As a result, her evidence could be crucial for an unsolved investigation into the murders police say were a professional hit. Police say they have interviewed more than 100 people in the biggest investigation in the country’s history.

“A prosecutor from the Special Prosecutor’s Office issued a warrant to copy part of the data from the cell phone that are necessary for the criminal prosecution. (Holcova) gave up her phone voluntarily,” the office said in a statement.

Holcova said: “I offered to give the police copies of my conversations with Kuciak but they also asked for access to my email and all mobile applications as of January 1, 2016.”

“I was told I could be fined up to 1,650 euros for refusing to cooperate. My phone was then confiscated and allegedly sent to a Europol forensic laboratory,” she said in a statement.

Police questioned Holcova for eight hours on Tuesday and confiscated her phone using a warrant from the Special Prosecutor’s Office, according to the Organized Crime and Corruption Reporting Project (OCCRP).

The international group for investigative reporters said Holcova’s phone contained information on other stories she was working on and demanded that police return it.

“The actions of the National Crime Agency are hostile and seem to point to an investigation of reporters and not the murder of Jan Kuciak,” it said in a statement. Holcova is an independent journalist who works under the OCCRP’s auspices.

The Slovak Press Publishers’ Association and editors in chief of Slovakia’s main newspapers condemned the police action in a statement, saying source protection is a pillar of journalism.

The country’s biggest protests since the fall of communism led to the resignation of Prime Minister Robert Fico and the formation of a new cabinet by the same three-party coalition. Senior Smer member Peter Pellegrini became prime minister.

The police chief also resigned under pressure and the new interior minister is expected to name a new police chief this month.

Kuciak’s last story probed links between Italian businessmen in Slovakia, one of whom was arrested on a European warrant for drug trafficking in March and extradited to Italy this week, and two Slovaks who later went on to work in Fico’s government office. All have denied any wrongdoing.