A leading anti-government activist in Ukraine who had been missing for over a week has turned up alive – but covered in blood.

Dmitry Bulatov claims he was abducted, tortured and had part of his ear cut off by men with Russian accents, before he was dumped in the countryside outside Kyiv.

“I was crucified, nailed. They cut my ears and face. And I have wounds all over my body. But thank God, I’m alive,” he said as he showed off his wounds to reporters.

Doctors say Bulatov has numerous cuts but no life-threatening injuries.

His AutoMaidan group organised anti-government protest motorcades and used cars to ferry supplies to protesters.

In Kyiv demonstrators hold President Yanukovych responsible for attacks on their protests and are sceptical of his decision to go on sick leave.

“He lacks the willpower to tell the people personally: ‘I made a mistake, I was wrong, this was terrible, these crimes must be punished’. He lacked the willpower… he pretended to be sick,” said one protester in Independence Square.

The opposition say seven people have died in the protests. One activist’s body was found dumped in a forest, not far from where Bulatov was found alive.

At least one leading opposition sympathiser, billionaire businessman and politician Petro Poroshenko, has suggested the same group carried out both attacks.

The United Nations' human rights office called for an investigation into reports of kidnappings and torture, and European Union foreign policy chief Catherine Ashton said she was appalled by the signs of torture inflicted on Bulatov.

“All such acts are unacceptable and must immediately be stopped,” Ashton said in a statement. “It is the authorities’ responsibility to take all necessary measures to address the current atmosphere of intimidation and impunity which allows for such acts to take place.”

“We are appalled by the deaths reported in recent days in Kiev, which should be promptly, thoroughly and independently investigated. We are also calling for an investigation into reports of kidnappings and torture,” Rupert Colville, spokesman for UN rights chief Navi Pillay, told a briefing in Geneva.