Riga - Workers were busy replacing paving stones into the cobbled streets of Riga's Old Town Wednesday morning hours after they were used to smash the windows of the Latvian parliament building.

A political demonstration Tuesday night degenerated into the worst civil unrest the Baltic state has seen for years.

Speaking on Latvian television Wednesday morning, Prime Minister Ivars Godmanis warned that the 106 people arrested "will not go unpunished," and defended police tactics in bringing the riot under control.

Next time, Godmanis warned, the police response would be even tougher.

He also said political protests might be banned from the Old Town in future.

Regular police and special riot units fought running battles with rioters, who were mainly young people, for nearly three hours. Witnesses told Deutsche Presse-Agentur dpa tear gas was used, though police refused to confirm it was they who had used it.

Baton charges were used to restore order after a crowd several hundred strong attacked the Latvian parliament building with paving stones, smashing windows and doors.

At one point heavily armed elite paramilitary units took up positions inside the building, apparently preparing to defend it if the crowd tried to force its way inside.

An off-licence was looted, 14 police cars were damaged and 10 policemen received medical treatment.

Police eventually managed to contain rioters in narrow streets directly opposite the parliament building.

The violence was in stark contrast to the peaceful political rally that preceded it.

Around 10,000 Latvians gathered in the central Dome Square to protest against a range of government policies by singing songs and waving banners calling on Latvian president to dissolve the parliament.

Before the rally, fears had been expressed that the night could end in violence after rumours spread on the internet that some groups were seeking a confrontation, and though most attendees at the rally appeared to be normal students, pensioners and workers, dpa also noted the marginal presence of some strange bedfellows: neo-Nazi Latvian groups, extreme Russian nationalists and anti-gay protestors.

Aigars Stokenbergs and Artis Pabriks, two former government ministers who addressed the rally, made a point of calling for peaceful protest, but their pleas went unheeded by some sections of the crowd.

Andris Dzenis, head of Riga central police department, said on public radio Wednesday that the early stages of the violence appeared to have been planned in advance but that the riot had then developed its own momentum.

However, it seems clear that whatever the reasons for the violence, there is little similarity with the last episode of civil disorder to rock the Baltic states.

In Estonia in April 2007, thousands of mainly Russian-speaking youths ran riot in the capital, Tallinn, after the government announced plans to relocate a Soviet war memorial.

In contrast, the Latvian rioters included both Latvian and Russian speakers, a fact confirmed by all eyewitnesses dpa spoke to on the scene. (dpa)