A member of the Ukrainian armed forces assists local residents onto a bus to flee the military conflict, in Debaltseve, eastern Ukraine in February 2015. (Gleb Garanich/Reuters)

MOSCOW — First, it was nationalist Ukrainian hackers, who were angry that journalists had accredited with separatists in southeast Ukraine. Then, it was pro-separatist hackers, who had stolen a list of journalists accredited with the Ukrainian government to cover the conflict.

Twice this month, the names, telephone numbers, e-mail addresses, affiliations, and travel dates of thousands of journalists, as well as human-rights activists, were leaked onto vigilante websites that have been used to unmask opposing fighters in southeast Ukraine's two year-old war. The leaks, and the official reactions to them, have revealed a deep suspicion of journalists who travel to both sides of the conflict and of their mandate to negotiate for permission to report from the local authorities, whoever that might be. One senior Ukrainian official called critics of the leak "liberal separatists."

In many cases, the hackers from both sides were targeting the same reporters. Journalists who have traveled to rebel-held Ukraine from Kiev say they have to accredit with both sides in the conflict in order to safely pass checkpoints and gain access to reporting targets. The accreditation isn't always enough to ensure safety. Vice News reporter Simon Ostrovsky was blindfolded, beaten and tied up with tape, before being detained for three days by separatist forces.

There were also questions about why openly patriotic Ukrainian journalists ended up on a list posted by a patriotic Ukrainian website.

No one has taken responsibility for the separatist list, which appeared on an anonymously run site that bills itself as anti-fascist and allows readers to submit the names, addresses and telephone numbers of members of pro-Ukrainian military and paramilitary groups. It also allows users to type in the telephone numbers of family members, examples of which include "wife Natalya" and "daughter Kristina." Anyone with an Internet connection can access the information.

But the pro-Ukrainian site, called Myrotvorets or "Peacekeeper," is championed by several senior Ukrainian government officials, including Interior Minister Arsen Avakov and his adviser, Anton Geraschenko. The site, which says it is run by anonymous volunteers, published the first list of Ukrainian and foreign journalists on May 12. The list, which was hacked from a computer used by the press office of the Donetsk People's Republic, should be published, the hackers said, "because these journalists collaborate with fighters from terrorist organizations.”

Myrotvorets, which also publishes the names and addresses of pro-separatist fighters, has been accused of providing targets for violent reprisals. Two days before the pro-Russian journalist Oles Buzina was shot dead in Kiev last year, his name and home address were published on Myrotvorets.

The leak prompted a sharp backlash. An open letter signed by 38 Ukrainian and international correspondents said that some of them had received threatening phone calls and e-mails.

"Accreditation does not mean and has never meant the cooperation of journalists with any of the conflict sides," the open letter read. "Accreditation is a form of protection and security for journalists."

The U.S. State Department said it was "concerned," about the leak, and the Committee to Protect Journalists, a New-York based journalist advocacy group, wrote an open letter to Ukrainian President Petro Poroshenko, calling the Myrotvorets leak a "deliberate attempt to intimidate journalists and potentially to put them at risk."

Far less is known about the separatist list, which appeared last week and which some called a "revenge leak." Ukraine's Security Service says that it did not publish the list, calling it a "fake." But those on the list (including me) have said that the information is correct and matches their own trips to Ukraine.