CHISINAU - Thousands of youth protesters stormed the parliament and presidency in Moldova Tuesday after a rally against a Communist election victory boiled over into violence in Europe's poorest country.

Moldova's ruling Communists -- the first Communist Party to win power in the former Soviet Union -- swept the weekend's legislative elections by winning half the vote, according to official estimates.

But the liberal opposition denounced the results as flawed and around 15,000 demonstrators according to the organisers turned out in the streets for a second day, hurling stones at the presidency and burning Communist flags.

Communist President Vladimir Voronin, who is due to to step down as president on April 7 after a maxiumum two consecutive terms, accused the demonstrators of trying to "destabilize" the country.

"The protests will continue until a date is set for new elections," said Chisinau Mayor Dorin Chirtoaca, deputy head of the Liberal Party, one of three liberal opposition parties beaten by the Communists in the vote.

"The protests are justified, their participants are calling for justice to be restored," he said.

Mark Tkachuk, the head campaign official for the Communist Party, described the day's events as "nothing other than an attempted overthrow of the government."

Police used water cannon and tear gas but the protestors still managed to enter the presidency and hoisted a European Union flag, an AFP correspondent reported.

They also dragged furniture out of the parliament building and set it on fire, filling the air with thick black smoke.

Over 30 people including both protestors and police were injured in the clashes, the head doctor at Chisinau's emergency hospital told AFP. A woman died from carbon monoxide poisoning after inhaling fumes in the parliament blaze, Moldova 1 television reported.

The demonstrators, who included many supporters of liberal opposition parties defeated in Sunday's elections, shouted slogans including "Freedom" and "Down with the Communists", the correspondent said.

The protestors burned Communist Party flags and the flag of the Soviet Union. They also shouted "We want to join Europe!" and "We are Romanians!"

Romanian is the official language of Moldova, which was part of Romania in the interwar period before being annexed by Soviet leader Joseph Stalin in World War II to become part of the USSR.

Moldova is predominantly agricultural country of 4.3 million people where the average monthly wage is only 253 dollars. Over a quarter of its active population works abroad and their remittances are vital for its economy.

The Communist victory in the legislative elections means it should have enough seats to choose the next president. Analysts expect Voronin to maintain a considerable influence.

EU foreign policy chief Javier Solana said he was "very concerned" about the unrest.

"Violence against government buildings is unacceptable. Equally important is the respect for the inalienable right of assembly of peaceful demonstrators," he said.

Russian Deputy Foreign Minister Grigory Karasin said Moscow was following the situation "with concern". He said the violence had been "provoked" but did not specify by whom.

Most demonstrators appeared to be under 25, many of them first-time voters in Sunday's polls and patently disillusioned by the result. Many had learned about the rally in an SMS text message campaign.

Vlad Filat, leader of Moldova's Liberal Democrats -- one of the vanquished parties in the election -- joined other opposition chiefs in criticising the vote but appeared taken aback by the size of the protests.

He and other opposition leaders later held talks with the government but failed to reach agreement on their main demand for a recount of the election.

"We have not received an official answer. Therefore our action will continue and we call on our supporters to behave in a civilised fashion and not give into provocation," he said.

The protests had started on Monday with a gathering of thousands of people in central Chisinau organised by a youth-led umbrella protest group called "I am An Anti-Communist".

Voronin's Communist Party of Moldova (PCRM) won around 50 percent of the vote in the parliamentary elections, which the Organization for Security and Co-operation in Europe (OSCE) said met "many" international standards.

The communists were followed in a distant second place by the Liberal Party, Liberal Democrats and Our Moldova parties, who won around 35 percent of the votes between them.

The Communists, who have pledged to build a "European Moldova" while also maintaining friendly ties with Moscow, came to power in 2001 and were re-elected in 2005.