A Ukrainian activist who went missing during anti-government protests has stumbled into a village near Kiev saying he was beaten and tortured.
Dmytro Bulatov, 35, told Ukraine's Channel 5 television: "They crucified me, they nailed down my hands. They cut off my ear, they cut my face. There isn't a spot on my body that hasn't been beaten."
Mr Bulatov, a member of Automaidan, a group of car owners that has taken part in the protests against President Viktor Yanukovych, was reported missing on January 22.
In the television interview his face and clothes were seen covered in clotted blood, his hands were swollen and bore the marks of nails.
Protesters in central Kiev after clashes with riot police He is among several activists whose disappearances have increased tensions the country.
One of the activists, Yuriy Verbytsky, was found dead in a forest while another, Igor Lutsenko, survived a severe beating and was hospitalised.
Opposition leader Vitali Klitschko, who visited Mr Bulatov in hospital, said: "What was done to Dmytro was an act to frighten all citizens who are being active now."
The UN's human rights office has called on Ukraine to launch an independent investigation into deaths, kidnappings and torture during the weeks of political unrest.
An anti-government protester at the site of clashes in Kiev Rupert Coville, spokesman for the UN high commissioner for human rights, said the issue "should be promptly, thoroughly and independently investigated".
The UN statement came as Russia's outspoken Deputy Prime Minister Dmitry Rogozin tweeted that US Secretary of State John Kerry's planned meeting with Mr Klitschko was a "circus".
The talks on Saturday are also expected to include Ukraine's pro-opposition popstar Ruslana.
Russian Deputy PM Dmitry Rogozin ridiculed US talks with the opposition Mr Rogozin suggested: "It's also necessary to involve Verka-Serdyuchka in the talks," referring to a Ukrainian drag queen popstar.
"Her/his authoritative opinion should be heard by the White House and taken into account!"
Meanwhile, President Yanukovych, 63, who sparked protests when he backed out of an agreement to deepen ties with the European Union in November, has taken sick leave.
Mr Yanukovych decided the ex-Soviet republic should strengthen ties with Russia.
The embattled leader, who has an acute respiratory illness and high fever, has already lost his prime minister Mykola Azarov, who resigned on Tuesday.
Ukraine's armed forces today urged the president to take "urgent steps" to ease the crisis, entering the fray on a political level for the first time.
"Servicemen and employees of Ukraine's armed forces ... have called on the commander-in-chief (Mr Yanokovych) to take urgent steps within the limits of existing legislation with a view to stabilising the situation in the country and reaching consent in society," the defence ministry said in a statement.
They "noted that a further escalation of the confrontation threatens the country's territorial integrity," the statement added.
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