A few of the captives have been released after pressure from human-rights groups. Friends of Ms Krat are approaching international organisations for help.
One of them, Oleg Veremeenko, a lawyer in Kiev, said: "She was crazy to go there [to the east]. But I couldn't talk her out of it". He is among a group now knocking on doors to get her released.
But Ms Krat is regarded as a valuable asset by her captors, not least in the propaganda war. The 29-year-old woman is a journalist and an activist; not just an activist but one of the few women to serve with militia groups in the Maidan, the centre of protest in Kiev which overthrew the government of Viktor Yanukovych.
In particular, it has been claimed, she was linked to the Patriots of Ukraine, ultra-nationalists regarded as bedfellows of the Right Sector, regularly attacked as Nazis in this area.
Ms Krat arrived in the east from Kiev at the start of the Easter weekend, posting Facebook messages from the city of Kramatorsk where Ukrainian troops, sent on an anti-terrorist mission to retake government buildings seized by protesters, have taken refuge at the airport after having their own armoured personnel carriers seized.
On Sunday, she arrived at next-door Slovyansk; it was a bad place to be at a wrong time. The city has become a formidable bastion for the militant movement, its police station occupied by some of the best-trained fighters among the secessionists; many of them former soldiers and police officers. Furthermore, just hours earlier, there had been an attack on a checkpoint, with Right Sector blamed for three killings.
Tension was high in the aftermath, with militiamen accusing foreign journalists of being spies. Ms Krat was swiftly arrested. Her Facebook page shows her with men with armbands which looked like the Wolfsangel, an emblem favoured by the extreme right. In any event she had been vocal and prominent as a leader of the Womens' 100 organisation, which guarded protest camps in the Maidan.
A man in a balaclava who described himself as an officer in the People's Guard declared that she had been among those who had mistreated Sergiy Rulyov, who was kidnapped and allegedly had his fingernails pulled out for "revealing" that the riot police unit, Berkut, did not initiate the shooting in which more than 80 people were killed during the uprising."
"No, I only knew these people, I did not have anything to do with torture. Of course, I agree that there should be an investigation into what happened, I am against such things," she protested. "I came over here to give voice to people who have not been heard, I would not abuse people. I want to say sorry, but they shouldn't put all the evil on me."
Mr Rulyov, who was seen as a collaborator by the protest movement, claimed that he was punched and kicked before needles were inserted under his fingernails on 5 March. "One of them was a woman in a headscarf, she did not say anything, but repeatedly kicked me in the groin", he said in an interview: Ms Krat was named on his Facebook page as the assailant.
On Sunday evening Ms Krat was interviewed with a bag over her face by Life News, a Russian website which has close ties with the security establishment. In footage distasteful to watch, the reporter parroted the statement of the separatists: "The peoples' militia has stopped a provocation by the head of the Maidan cell before being harangued about what she was doing here."
Yesterday, the same young female reporter acted as spokeswoman for the separatists, telling journalists not to block the entrance to their sandbagged base. Ms Krat was repeatedly asked whether she regretted being on the Maidan. Her response was: "We did not know then what we know now. There is no point in talking about that now, we should think about the future."
What about the prospect of her being exchanged for prisoners being held by the Kiev administration? "I am not a dog to be traded. I will get out of here by my own efforts; I have done nothing wrong," was her defiant reply.
Three other journalists, two Italians and one from Belarus were arrested, but later released in Slovyansk yesterday. But the mayor, Mr Ponomaryov, had a warning for the media: "Those who don't report things truthfully will be thrown out of the city. We are watching you."
- The Independent