Historic documents from the Ottoman era have been damaged in Bosnia's recent riots, officials said Monday, as demonstrators pressed on with protests against corruption and unemployment in the country's worst upheaval since the 1992-1995 war.

Sarajevo's state archives building was engulfed in flames Friday after protesters set fire to the nearby presidential building in an explosion of popular anger.

The full extent of the destruction is still being investigated but one of the affected depots housed the "oldest documents from between the Ottoman Empire times and World War II", the state archives' management said in a statement.

Documents spared by the fire were later waterlogged during the firefighters' intervention, it added.

"This is a catastrophic damage for Bosnia as the documents that were destroyed can not be restored," Admir Jerkovic of the archives told AFP.

"The hooligans who set the fire have burned Bosnia's memories. This is a crime against the Bosnian people."

Meanwhile, some 200 demonstrators took to the streets for a sixth consecutive day in the capital, where city workers were still clearing the debris from the recent rioting.

Fresh protests were also held in several other Bosnian towns.

The turmoil first erupted on Wednesday in Tuzla, once the biggest industrial hub in Bosnia, with locals venting their fury over years of political inertia and economic hardship.

The protests quickly spread across the country, leaving hundreds injured while a number of local government buildings were ransacked and set alight over three days. Daily demos have continued sine then but they have been smaller and more peaceful.

Two parties in Bosnia's ruling coalition have called for early polls to ease tensions in the Balkan nation, where unemployment stands at 44 percent.

The protesters are also demanding the resignation of the government of the Muslim-Croat federation, one of the two entities which together with the Serb Republic makes up post-war Bosnia -- a complex arrangement that critics say has slowed down reform efforts and led to a weak central government.

So far, four regional officials in the federation have stepped down under pressure from the protesters.

Political blame game

Bosnia has responded with shock to the violent nature of the protests, the country's worst unrest since the end of the 1990s war which left more than 100,000 dead.

Today, Bosnia is one of Europe's poorest countries with an average monthly salary of 420 euros ($570), and corruption among the political elite is seen as widespread.

"Maybe early elections can be a remedy to stop" the violence, said Zeljko Komsic, a Croat member of Bosnia's tripartite presidency.

General polls are scheduled be held in October.

While Bosnia's leaders have been unanimous in condemning the violence and the destruction of public buildings, they have also been quick to blame each other for failing to prevent the trouble.

Bakir Izetbegovic, leader of the main Muslim SDA party, has accused the country's Security Minister Fahrudin Radoncic of failing to protect state institutions and of supporting the protesters.

Radoncic, a businessman-turned-politician, meanwhile warned that government inaction could spark more anger, calling for an anti-graft "tsunami".

Many protesters say they aren't interested in the political infighting, and want authorities instead to focus on fixing the ailing economy and tackling mismanaged privatisation deals that have left many unemployed.

"We do not belong to any political party, we are only dissatisfied citizens of Bosnia," said Emina Busuladzic, a protester in Tuzla.

Analyst Srecko Latal said there was no driving political force behind the protests.

"The main message is that the citizens are tired of the political class and they make no difference between the political parties," said Latal.