Volleys of shots rang out as the rioters broke into government headquarters housing the office of the Socialist prime minister, Fatos Nano. Armed police ejected them after they tried to torch the building.
Government cars were turned over and set alight by the demonstrators, supporters of the right-wing Democratic Party leader and former president Sali Berisha, himself ousted in an armed uprising last year. One demonstrator was said to have been killed and four police officers wounded.
The unrest follows the weekend murder of a leading Democratic Party politician Azem Hajdari, shot dead near opposition headquarters in Tirana by attackers in police uniforms.
Mr Berisha yesterday claimed the killing was a political assassination organised by the government and he called on the prime minister to resign within 24 hours "to avoid the worst".
Mr Berisha told the BBC World Service: "The country is in the most dramatic moment it could be."
Tirana is abuzz with rumours about why Mr Hajdari, a former student leader, was killed. But the claim that the authorities were behind the murder was dismissed by political analysts as "absurd".
Yesterday's riots showed that the Albanian government is unable to maintain order, even in the capital, when confronted by a direct challenge. Few believe it would be in the Socialists' interests to provoke unrest by killing one of their opponents. The government also yesterday condemned the murder and announced a $100,000 reward to catch the killers.
Among the theories circulating in Tirana is that Mr Hajdari was a casualty in the gang war to control the lucrative black-market in weapons being smuggled to ethnic Albanian rebels in Serbia, the Kosovo Liberation Army. He was from the northern town of Tropoja - the centre of operations for weapons smugglers - and one source close to the KLA said Mr Hajdari's clan was involved in the trade.
Others say Mr Hajdari was killed in one of Albania's traditional blood feuds, or even that he was murdered by the Serbian secret police. Mr Berisha's opponents are circulating the opinion that the former president had a hand in the killing, or is taking advantage of it.
"He is trying to organise a civil war to get back into office," said one Tirana political insider and long-standing critic of Mr Berisha. "He has been threatening to do this for a long time and now it has started."
Mr Berisha was elected in 1992, Albania's first democratic leader after 50 years of a brutal Communist dictatorship which had closed the country to the outside world and left its citizens the poorest in Europe.
But five years later, he was ejected from office after widespread protests about fraudulent pyramid investment schemes - in which most Albanians lost money - turned into armed insurrection.
The former president claimed yesterday that he would not try to take advantage of the current unrest to usurp power and denied trying to whip up supporters.
He pledged that the Democratic Party would not take office again until the Albanian people had voted in a new election.
"A political solution is vital for this country," he said. Tension is rising as the end of Mr Berisha's 24-hour deadline for the prime minister to resign approaches later today.
Some see the unrest as a side effect of the war in Kosovo. Albania is a refuge for soldiers of the Kosovo Liberation Army, regrouping as it suffers defeat after defeat at the hands of the Serbian security forces.
Mr Berisha has been vociferous in his support of the Kosvars, accusing the Socialist government of watching while genocide is committed against their ethnic kin. His opponents claim that KLA fighters may well be used by Mr Berisha if civil war does break out in Albania.
Last night there were unconfirmed reports that Democratic Party supporters had set up roadblocks on the national highway outside Tirana.Reuse content