Ukraine's acting president called for an anti-terrorist operation to be relaunched in the east of the country on Tuesday 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 councilor 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 on Tuesday. She is running in the presidential election scheduled for May 25.
The United States has offered Ukraine a new $50 million aid package to help with economic and political reform, the White House said on Tuesday during a visit to Kyiv by Vice President Joe Biden.
It also offered an additional $8 million in non-lethal military aid, including radios and vehicles, according to a statement issued by Biden's staff in Kyiv.
Small in terms of Ukraine's needs and in relation to the $1 billion loan guarantee already signed with Washington, the package, along with Biden's visit, was a clear show of support for the new authorities following the overthrow of the Kremlin-backed president and continuing confrontation with Russia.
"The United States is committed to ensuring that Ukrainians alone are able to determine their country's future without intimidation or coercion from outside forces," it said.
Saying Washington was ready to provide further assistance after a presidential election on May 25, it said $11.4 million of the package would support the integrity of that vote.
US experts would also work on reducing Ukraine's dependence on Russian gas and in fighting corruption.
Meanwhile, Ukrainian Prime Minister Arseny Yatsenyuk said on Tuesday that Russian special forces were operating in eastern Ukraine to undermine a presidential election due on May 25 and he called on Moscow to pull them out.
At a news conference after meeting Biden, Yatsenyuk also urged Russia to remove its troops from Crimea, annexed by Moscow last month.
"Everything that is now happening in the east and which Russia is supporting is aimed at wrecking the presidential election," Yatsenyuk said.
"We demand that our Russian neighbors immediately recall their special forces, which are in the east, recall the army from Crimea and turn this shameful page in which Ukrainian territory has been seized by Russian troops."
Thanking the United States for its support, following offers of aid during Biden's visit that is intended to help ensure a viable election and to fight what Biden called the "cancer" of endemic corruption in Ukraine, Yatsenyuk said: "The Ukrainian government understands that money is only given to those countries which are truly fighting corruption.
"One of the key tasks of my government and the new president will be the struggle, and victory over corruption."
He also said he would welcome "the widest possible" cooperation with US and EU companies in the energy sector, which would help Ukraine reduce its dependence on Russian gas.