Thousands of Bulgarians renewed calls for the government to resign over corruption and a host of economic problems, including a cut-off in gas supplies, in a second day of protests on Thursday.

Police deployed in large numbers in front of parliament to try to prevent a repeat of Wednesday's unrest in which rioters, including students and farmers, clashed with police and smashed windows in some of the worst violence in Sofia in 12 years.

"We want the government to step down," said student Adriana Ivanova, 23, one of the protest organisers. "We want a better life in Bulgaria and we are ready to keep rallying until we see a change."

Many Bulgarians say they are fed up with the quality of life in the Balkan country of 7.6 million, which has the lowest GDP per capita in the European Union.

Much anger has been directed at the government's failure to stamp out endemic graft and organised crime, and its delay in pushing through reforms to cushion the impact of the global financial crisis.

A gas row between Russia and Ukraine, which has stopped flows to Bulgaria, has added to the discontent which analysts say is likely to grow before this year's parliamentary election.

"The average Bulgarian is in a very difficult situation because he has a very low income and almost no savings ..." said Ognyan Chipev, a 53-year-old engineer. "The government kept saying we shouldn't worry ... This was frivolous and irresponsible," he added.

Anger over the authorities' handling of the global economic slowdown has also sparked riots in Latvia, Iceland and Russia.

MORE PROTESTS PLANNED

Students, farmers and green activists have threatened to hold more rallies in the coming weeks. Police are planning to protest over low salaries and poor work conditions on Saturday.

Opposition right-wing parties have also called for the cabinet to resign. The nationalist Attack party, which has 11 deputies in the 240-strong chamber, said it was quitting the parliament as it no longer "represented people adequately".

Wednesday's riot was the worst since 1997, when 30 days of mass rallies and strikes toppled the then Socialist government for pushing Bulgaria into an economic meltdown.

Analysts said Prime Minister Sergei Stanishev's ruling coalition was not threatened, despite plummeting support, because it has an overwhelming majority in parliament.

"The government is obviously having serious problems ... but for now there are no signs of political destabilisation," said Rumiana Kolarova, political analyst at Sofia University.

"Whether the protests can topple the government depends on how they unfold and whether they manage to attract more people," she added.

The government took Bulgaria into the European Union last year, nearly halved unemployment to 5.8 percent, almost doubled pensions and public sector wages and has attracted 6 billion euros of foreign investment a year since it took power in 2005.

But growth is likely to slow by up to 2 percent this year as Bulgaria's main export market, the EU, faces a deep recession.

Brussels froze EU aid to Bulgaria last year over rampant graft and Transparency International portrayed the country as the most corrupt EU member.

Take a look at the yesterday's events in VIDEO: Fed up Bulgarians riot