Ukraine's embattled president has sought to quell public anger by renewing talks with Brussels after massive anti-government demonstrations besieged government buildings and called for the removal of the ruling party.

President Viktor Yanukovych called the European Commission President Jose Manuel Barroso on Monday and asked to renew negotiations on signing the association agreement.

The Ukranian president has struggled to reaffirm his grip on power as thousands of demonstrators besieged government buildings in Kiev, rallying against his decision to abandon a deal for closer ties with the EU swept the country and threatened his rule.

The rally has been mostly peaceful until a group of protesters tried to storm Yanukovich's office and police chased protesters away with tear-gas and truncheons, injuring dozens.

Al Jazeera's David Chater, reporting from Kiev, said the government had ordered 1,000 Interior Ministry troops to secure government buildings, as the number of protesters grew.

"The blockade is severely disrupting the process of government here," he said.

"Essentially, President Yanukovich has lost control of the centre of Kiev."

It was a violent police action against protesters early on Saturday that galvanised the latest round of protests, whose aim is to bring down the president and his government.

At least three politicians of the governing Party of Regions have quit in protest and one of them, Inna Bohoslovska, previously a vocal government supporter, called on other legislators to leave the party.

A top Agriculture Ministry official also resigned on Monday.

Confidence vote

The opposition hoped to topple the cabinet of Prime Minister Mykola Azarov during a confidence vote in parliament on Tuesday.

The opposition, which now controls about 170 seats, would need 226 votes in the 450-seat Rada.

Oleksandr Yefremov, head of the Party of Regions faction in parliament, said politicians would discuss the situation on Tuesday morning and might then put a no-confidence motion up for a vote, but he said there were no grounds to dismiss the government.

Yefremov said the opposition's goal was to calm protesters in Independence Square down.

Vitaly Lukyanenko, Azarov's spokesman, said the government was not planning to impose a state of emergency.

He told the Interfax news agency that because government employees could not access the cabinet building, they would work online.

Opposition calls for a strike were being headed by local governments in western Ukraine, where most people speak Ukrainian and lean towards the EU.

In the industrial east of the country, most people tend to speak Russian and have a closer affinity for Russia.

Officials in the western cities of Lviv, Ivano-Frankivsk and Ternopil said they were going on strike and called on their residents to turn out for protests.

The mayor of Lviv said that police in his city would take off their uniforms and defend the city if the central government sent reinforcements.

Scores of protesters from Lviv and elsewhere in western Ukraine have headed to Kiev by train and car to take part in the rallies.

Economists were concerned what impact the protests would have on Ukraine's economy, which has been in recession for more than a year.