Kidnappings have been on the rise as the situation in eastern Ukraine has deteriorated.

Before VICE News correspondent Simon Ostrovsky was released, Vyacheslav Ponomaryov, Sloviansk’s self-appointed “people’s mayor," told reporters that he and the other detainees were being held as “bargaining chips” in negotiations with authorities in Kiev.

"Pro-Russia militants in eastern Ukraine are holding dozens of people hostage, as I found out through personal experience last week when I was kidnapped at a checkpoint in Sloviansk," Ostrovsky said upon being released. "I saw many detainees filter through the damp cellar I was being held in for three days, and in between being beaten, and blindfolded, and sleeping on dirty rags on the floor I managed to get to know four of them personally."

Being held with Ostrovsky were a journalist, a computer programmer, a local politician, and a bodybuilder, "who seemed only to be linked by the fact that they'd somehow upset the gunmen that now control the city," he said. But many more were and are still being held, in barely tolerable conditions.

Eastern Ukraine is lurching towards a May 11 referendum that is supposedly meant to give its residents the chance to freely decide to be part of Ukraine or to join Russia. But it's being pushed through at gunpoint, by forces who are interested in only one of those outcomes.

So it's worth remembering that the people calling for the vote are also depriving many people of their most basic freedoms right now, to the point where their prisoners have to ask someone for permission every time they want to use the toilet.

VICE News has put together a partial list of people who have been detained by Russia-supporting militants in eastern Ukraine. The list is not complete because details have been sketchy, but we will continue to update it as we learn more about these individuals.

The abductions and detentions have drawn widespread international condemnation.

“The ongoing detention of journalists, municipal officials and residents by an armed group in Sloviansk speaks volumes about the lawlessness that has crept into parts of eastern Ukraine, and raises fears the detainees could be at risk of torture and other ill-treatment,” Heather McGill of Amnesty International said in a statement last week. “Anyone unlawfully detaining journalists or others in eastern Ukraine must guarantee their safety and release them immediately and unconditionally.”

Here are some of the others who are still being held now.

Vitaliy Kovalchuk

Vitaliy Kovalchuk is a 21-year-old former member of the Euromaidan self-defense corps. He was detained on April 20 by separatists who claimed he was a member of the rightwing Ukrainian nationalist group "Right Sector." The group denied the allegation in a statement.

In the video below, by Russian TV channel Life News, Kovalchuk is paraded in front of reporters by masked, armed men.

Vadim Sukhonos

Vadim Sukhonos is a member of the Sloviansk city council. Last February he resigned from the Russian-speaking "Party of Regions" — Yanukovych's party — reportedly over personal disagreements with the party's line. The video below shows him speaking to reporters about his resignation.

Irma Krat

Photo via Getty

Irma Krat, a 29-year-old Ukrainian journalist and activist, has been held since April 20. She was paraded before reporters, blindfolded, by armed men who then removed her blindfold for the improvised press conference.

The men that detained her claimed that they were not holding her “against her will.” They have said Krat, a Euromaidan activist who runs an online publication, is suspected of being a “spy.”

Krat was reportedly a member of the Maidan’s “women’s brigade,” a group made up largely of journalists, lawyers, and intellectuals.

The video below shows Krat addressing reporters during her detention.

Denis Grishchuk and Paul Ûrova

Denis Grishchuk is a volunteer at the "Mystetskyi Arsenal" art center and Paul Ûrova is a theatre director. The two have been missing in Sloviansk since April 25, according to friends. The self-proclaimed mayor of Sloviansk confirmed to their families that they are being detained by his group, but refused to let them speak to them.

Sergei Shapoval

Sergei Shapoval, a reporter with Volyn Post, a news website based in the northwestern Ukrainian city of Lutsk, was reported missing on April 26, according to the Committee to Protect Journalists (CPJ). He has since contacted his family to confirm that he is being held by separatists in Sloviansk.

Yuri Lelyavsky

Yuri Lelyavsky is a correspondent for the Lviv-based ZIK media holding company, according to CPJ. He was abducted on April 25, while filming in the streets of Sloviansk. Other journalists reportedly witnessed the incident.

Recently Released

Serhiy Lefter - UPDATED (May 11, 2014)

Serhiy Lefter is a 24-year-old freelance journalist from Vinnytsia, in western Ukraine. He was abducted from the main square in Sloviansk by pro-Russia militants, on the evening of April 15. He has been held in the basement of the Ukrainian Stat Security building (SBU) for over two weeks now, which is where Ostrovsky met him. He had bruises under both of his eyes, but hadn't been beaten for a few days by the time Ostrovsky was captured, and was being treated decently. Lefter is now safe and was released on May 3.

Lefter said that he was captured because he was explaining the situation in Sloviansk at length to a colleague over the phone in front of the occupied city hall, and gunmen stationed there thought he was behaving suspiciously. He had been working for a Polish media NGO called the Open Dialogue Foundation for about a month at the time of his capture.

"The disappearance of Serhiy Lefter is yet another sign of aggression against journalistic environment," the group said in a statement on their website. "The Open Dialog Foundation is appealing to the members of the UN and the OSCE to recognize that the responsibility for the kidnapping of the Ukrainian journalist lies with the Russian Federation, which has been carrying out a military invasion in Ukraine."

"The Open Dialog Foundation is highly concerned that kidnapping and detention of journalists in eastern Ukraine may become a widespread practice, standing in the violation of basic human rights," the group added. "We are strongly convinced that distributing objective and independent information on Russian actions in eastern Ukraine among the international community may stop the Russian aggression."

Prior to arriving in Sloviansk, Lefter worked for the First National Ukrainian TV channel (Pierwyj Nacjonalnyj), the Open Dialogue Foundation said. He resigned while Yanukovych was still in power, after facing pressure and censorship of his work. Since then, he contributed to the Maidan24 online portal, and reported on the developing situation in Ukraine from Crimea, Kramatorsk, Donetsk, and Kharkiv. He arrived in Sloviansk a day before being abducted there.

Artyom Deyneha

Artyom Deyneha is a 25-year-old computer programmer and a resident of Sloviansk. He was detained by separatists for setting up a web camera to film the same SBU facility where he himself ended up being detained. Deyneha was able to run his live stream for three hours, before being abducted. Since then, the video was viewed more than 200,000 times.