Ukrainian riot police used batons and stun grenades to disperse hundreds of pro-Europe protesters early yesterday after a night of violence in Kiev following President Viktor Yanukovych's decision not to sign a landmark pact with Europe.

Black-helmeted police moved in on protesters camped on the capital's Independence Square, first firing grenades to disorient them and then wading in with batons, witnesses said. Police units chased several protesters into side streets.

A total of 35 people were detained for resisting police, the interior ministry said.

There was no official total for those injured, but the opposition said it could be as high as 100.

"It was absolute savagery. By my count, we are talking of tens of cruelly beaten people, perhaps hundreds," said an opposition deputy, Andriy Shevchenko.

Tension had been building in Kiev since Friday, when Yanukovych declined to sign the pact with European Union leaders at a summit in Lithuania, going back on a pledge to work toward integrating his former Soviet republic into the European mainstream.

He said the cost of upgrading the economy to meet EU standards was too great and that economic dialogue with Russia, Ukraine's former Soviet master, would be revived.

After the police action, about 200 demonstrators shifted their protest to St Michael's Cathedral - formerly a 12th-century monastery that was destroyed by Soviet authorities in 1937 and rebuilt after independence in 1991.

"We gathered here after riot police beat us and chased us out of the square. It's the only safe place we could go to," said 25-year-old Roman Tsaldo.

"Ukraine has woken up in a ­different state after Yanukovych refused to sign in Vilnius. It is no longer Ukraine. It's closer to ­Belarus," said opposition leader Arseny Yatsenyuk, referring to the neighbouring country that has been under one-man rule since 1996.

"Yanukovych has already started training for the (presidential) ­elections in 2015," said Yatsenyuk, a former economy minister.

"He will carry out the elections with the Berkut [riot police], special units, shields, helmets and batons."

The opposition said the riot police stormed into the encampment of protesters without warning.

"There were no grounds for it. There was no provocation by the crowd. People were singing, warming themselves by camp fires," said Shevchenko.

Heavyweight boxing champion turned opposition politician Vitaly Klitschko said: "After the savagery we have seen on Independence Square we must send Yanukovych packing."

"They undermined the ­agreement [with the EU] so as to untie their hands for outrageous behaviour which would be unthinkable by European standards," said Klitschko, a likely contender for the presidency in 2015.

At least four people were beaten by police earlier on Friday night, including reporters.

The tough police tactics set the scene for possibly more confrontation today, at a pro-Europe rally called by the opposition. About 100,000 people turned out last Sunday, flooding the city centre.

Speaking to crowds on Friday night, Klitschko said: "Today they stole our dream, our dream of living in a normal country. The failure to sign the agreement of association is treason."