* US and EU leaders clash with Moscow over Ukraine
* International concern at risk of instability
* Germany says "tortured" protester can fly for treatment
* Mutual accusations, violence, keeps nerves on edge
By Alastair Macdonald
KIEV, Feb 1 (Reuters) - Western governments pressed Ukraine's president to compromise with protesters camped on the streets, prompting a war of words with Russia on Saturday and offering treatment to an opposition activist who says he was tortured.
At an annual security conference in Munich, founded at the height of the Cold War, Ukrainian opposition leaders met U.S. Secretary of State John Kerry and European officials and the Russian foreign minister accused Western powers of fomenting protests against President Viktor Yanukovich.
Sergei Lavrov said the West had "imposed" on Ukraine to cooperate with its NATO defence alliance, while Kerry said the Ukrainian protesters believed "their futures do not have to lie with one country alone - and certainly not coerced".
Opposition leaders said they felt "huge support" after European Council President Herman Van Rompuy said closer ties to the EU were still on offer to Kiev and Kerry assured them that Washington and the EU "stand with the people of Ukraine" in "the fight for a democratic, European future".
The resignation in the past week of the prime minister and withdrawal of new laws curbing rights to protest have failed to appease demonstrators occupying public buildings and streets in Kiev and other cities who want Yanukovich out after he spurned a trade deal with the EU in November and sought Russian aid.
Reflecting fears that one of Europe's biggest countries may be lurching toward a civil war that could set Moscow against the West and destabilise the continent, Germany's foreign minister warned: "When the fuse on the powder-keg is already lit, playing for time is highly dangerous."
Frank-Walter Steinmeier urged Yanukovich to make good on a pledge to seek consensus. "Only then is there a realistic chance of a political solution to the confrontation," he added.
Fuelling anger against the authorities in the past two days have been images of a prominent activist who says he was beaten and "crucified" after his abduction a week earlier. The case of Dmytro Bulatov has drawn demands from the West for an investigation and anger at reports the victim faced arrest in hospital on the serious of charge of "mass disorder".
Steinmeier said he had secured the agreement of Ukraine's foreign minister, Leonid Kozhara, to let Bulatov leave the country for medical care and the U.S. ambassador visited the Kiev clinic where Bulatov was being treated. "It was a gesture of solidarity and support," an embassy official said.
Police said Bulatov was still wanted but would face only "house arrest". A senior police official complained that his officers had been unable to interview him to pursue the investigation of his abduction - and was also quoted as saying Bulatov may have invented the kidnap to provoke social unrest.
Kozhara was quoted by the Ukrainska Pravda news website questioning Bulatov's version and saying he was scarcely hurt.
The U.S. embassy official said the ambassador had not seen Bulatov as the 35-year-old activist was not conscious.
The director of the clinic said Bulatov had been overcome with emotion but was now stable and in fair medical condition.
Opposition lawmaker Petro Poroshenko was quoted as saying in Munich that Bulatov would fly to an EU country on Sunday.
A surge in violence last month saw at least six killed and scattered incidents and mutual accusations have continued to inflame passions on either side of deeply divided nation that finds itself at the centre of geopolitical tug of war.
Ukraine's Interior Ministry accused opposition activists of beating up a plainclothes police major in the basement of Kiev's occupied city hall. Opposition sympathisers complained of cars being torched overnight and highlighted an online claim of responsibility apparently from a pro-government militant group.
Security officials, commenting on computer drives seized two months ago from a party office, effectively accused the main opposition movement of plotting a coup when unrest broke out in November. The party's leader, a former prime minister, is in jail despite EU demands that she be freed on medical grounds.
Security officials were quoted in local media saying that data recovered from the headquarters of Yulia Tymoshenko's Batkivshchyna (Fatherland) party indicated that it had planned in advance the unrest that followed Yanukovich's rejection of the EU trade pact with the intent to "seize power".
Party officials made no immediate comment on the remarks.
Mirroring the emergence around protest camps of hardline, anti-Yanukovich squads in combat gear and carrying batons known as the "Right Sector", a meeting of supporters of the president's party in the mainly Russian-speaking eastern city of Kharkov approved the formation of a "Ukrainian Front" - a name recalling the World War Two victory over occupying Nazi forces.
Quoted by Interfax news agency, a senior local figure in Yanukovich's Party of the Regions called for veterans of the Soviet war in Afghanistan to join in a "national guard" to remove protesters from occupied public buildings.
Despite widespread discontent with Yanukovich over an economy in the doldrums and complaints of corruption, he still enjoys significant support, particularly in the east, as opposed to the mainly Ukrainian-speaking west. A poll by the Socis agency conducted from Jan. 17-27 found he would top a first-round presidential ballot with about 20 percent of the vote.
Former world champion boxer Vitaly Klitschko would run him a very close second, Socis said, although if Tymoshenko were free to run then she and Klitschko would be neck and neck at around 15 percent.
Klitschko, who was at the Munich conference, urged foreign leaders to pressure Yanukovich and said sanctions on Ukrainian leaders and the business magnates who support them, especially on those with investments within the European Union, would help.
"External pressure is very important," he told German radio.
Foreign Minister Kozhara told the conference "not all Ukraine supports" the protests and noted nearly a fifth of the 45 million population was ethnically Russian. "Do you think they are happy when European politicians say you must ... take Ukraine away from Russia and put it somewhere else?" he said.
Yanukovich issued a statement on Thursday saying he was on sick leave, though he has since signed legislation and critics have suggested he is trying to gain time after Batkivshchyna's Arseny Yatsenyuk refused to be prime minister.
Russian President Vladimir Putin has added to pressure, as Moscow is holding back financial aid until it is clear which new government will be formed in Kiev.
Government officials have in recent days said there could be a review of constitutional arrangements in parliament that might curb the presidency in favour of the legislature, but protesters on the street may not be satisfied by limited reforms.
Concern about violence escalating has prompted Ukraine's armed forces to issue assurances it would not become involved in civilian affairs. The defence minister said on Friday military personnel overwhelmingly supported the president's action and that, under the constitution, the military could only take action if there were a state of war or a state of emergency. (Additional reporting by Jack Stubbs, Pavel Polityuk and Richard Balmforth in Kiev and Stephen Brown, Missy Ryan and Alexandra Hudson in Munich; Editing by Robin Pomeroy)