Ukrainian protesters declared a general strike and continued their blockade of government buildings.

Anger at President Viktor Yanukovych's decision to ditch closer ties with the European Union has gripped other parts of the country and threatens his administration.

Thousands of protesters blocked entrances to the government building and called for the sacking of the prime minister and his cabinet.

A heavy cordon of interior ministry troops surrounded the building as ever-larger crowds gathered.

The siege follows a huge rally in the capital Kiev by 100,000 people on Sunday.

The rally was mostly peaceful, until a group of protesters tried to storm Mr Yanukovych's office.

After hours of violent scuffles, police chased protesters away with tear gas and truncheons.

Kiev council said yesterday that 165 police officers and demonstrators had been injured.

A brutal police action on Saturday galvanised the latest round of protests and caused the sacking of the local police chief.

At least three MPs of the governing Party of Regions have quit in protest and the opposition is aiming for a confidence vote tomorrow.

But the opposition, which now controls 170 seats, would need 226 votes in the 450-seat parliament to oust the government.

Government spokesman Vitaly Lukyanenko said there was no plan to impose a state of emergency.

In parts of the west, where most speak Ukrainian and lean toward the EU, some local officials seemed to be in open revolt.

The mayor of Lviv called for protests and warned police would take off their uniforms and defend the city if the central government sent reinforcements.

And Ivano-Frankivsk mayor Viktor Anushkevichus said he and his deputies were taking unpaid leave "in solidarity with the strikers."

In Kiev, thousands returned to Independence Square, where several hundred protesters had camped overnight.

Hundreds of others were holding ground inside the Kiev city hall and a trade union building where they had barricaded themselves on Sunday.