Ukraine's acting president called for an anti-terrorist operation to be relaunched in the east of the country after the body of a local politician from his own party was found showing signs of torture.
Ukraine's security forces had largely suspended what was a fairly limited operation to respond to the takeover of eastern town by pro-Russian separatists after an accord with Moscow last week to try and defuse the crisis. Oleksander Turchinov's call for action could complicate the task of European mediators.
The acting president said in a statement that two "brutally tortured" bodies had been found near the city of Slaviansk, which is in the hands of pro-Russian militants. One was that of Volodymyr Rybak, a member of Turchinov's Batkivshchyna party, who had recently been abducted by "terrorists".
"These crimes are being carried out with the full support and indulgence of the Russian Federation," he said. "I call on the security agencies to relaunch and carry out effective anti-terrorist measures, with the aim of protecting Ukrainian citizens living in eastern Ukraine from terrorists."
In a statement from regional headquarters in Donetsk, police said the body of a man who died a violent death had been found in the Seversky-Donets river and that it resembled Rybak, a local councillor in the town of Horlivka, near Donetsk.
Formal identification would need further work, police said. Local media said Rybak was abducted in Horlivka, a nearby locality, on Wednesday last week.
Batkivshchyna leader Yulia Tymoshenko, a former prime minister and great rival of the ousted Kremlin-backed Ukrainian president, was visiting Donetsk earlier today. She is running in the presidential election scheduled for May 25.
Supporters of Ms Tymoshenko were pelted with eggs by pro-Russian separatists as they went to her rally.
The protesters shouted slogans outside the regional government building in Donetsk, in eastern Ukraine.
The latest trouble comes as US Vice President Joe Biden told Russia that "time is short" for action on defusing the crisis in eastern Ukraine, but Moscow refused to be rushed, saying it could handle any tougher economic sanctions the West might impose.