Hungary's opposition parties called on Tuesday on Prime Minister Ferenc Gyurcsany to quit after thousands of people took to the streets in a night of anti-government riots in which 150 people were injured.

The riots, the worst in Hungary since the end of communism, were triggered by the leak of a tape on Sunday in which Gyurcsany said he and his Socialist party had lied for four years about Hungary's parlous budget in order to win April's elections.

Streets were calm on Tuesday and only about 50 protesters were left in front of the parliament building and police presence appeared light.

The initially peaceful demonstration of around 10,000 people in front of parliament turned violent as some protesters stoned and set fire to the state television building, occupied part of it and looted it. Some 150 demonstrators and police were injured.

"There is a moral crisis unfolding and Ferenc Gyurcsany should make it clear that his comments referred to their period in government," Tibor Navracsics, opposition Fidesz faction leader told state television MTV.

The Fidesz call was echoed by the smaller Hungarian Democratic Forum, whose leader Ibolya David told MTV "the prime minister should abandon public life."

Gyurcsany, facing the biggest challenge to his two year premiership with the riots, won April's election partly on a promise of tax cuts but has since imposed tax rises and benefit cuts worth 4.6 billion US dollar in 2007 alone to curb Hungary's budget deficit which will surge to 10.1 percent of gross domestic product this year.

He has vowed to stand firm and received backing from his Socialist Party to remain prime minister and to implement his economic policies, which the opposition has characterized his government as "illegitimate."

According to a snap poll of 500 people on Monday by pollster Szonda Ipsos, 43 percent of people thought Gyurcsany should resign immediately, while 47 percent said he should stay and 10 percent had no opinion.

Investors who hold billions of dollars of Hungarian bonds are worried that Gyurcsany may be forced out of office or to abandon his economic policies, which most economists see as the only way to rescue the country's parlous finances.

On Tuesday, the forint weakened slightly against the euro from five week highs on Monday, and was trading at 272.45 to the euro by 0720 GMT, down 0.8 percent from Monday's close and economists are concerned that more violence will come.

"This also makes it much more likely that the government will have to abandon at least parts of the planned fiscal austerity measures," said Lars Christensen at Danske Bank in a research report on Tuesday.

Hungary's Prime Minister Ferenc Gyurcsany said on Tuesday he would crack down if there were a repeat of the violence and he received support from the Socialist coalition partner, the alliance of Free Democrats on Tuesday.

"The biggest irresponsibility possible would be for the prime minister to resign. The prime minister is legitimate and should continue to implement his program," Gabor Kuncze, leader of the Free Democrats told MTV on Tuesday.

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