|Demonstrators gathered to protest the arrest of Tihomir Purda, in Bosnia, on charges of war crimes [EPA]
Thousands of people have demonstrated in the main square of Zagreb, Croatia's capital, to support veterans of the 1991-1995 independence war, according to police.
Organised by a war veterans group, Saturday's demonstration was the largest of its kind, since a wave of similar gatherings was sparked by last month's arrest of Tihomir Purda in Bosnia.
Purda has been detained on charges of war crimes and could be extradited to Serbia. However, he denies any wrongdoing and told the judges in Bosnia that his confession in Serbia was made under torture.
The final ruling on Serbia's request is pending.
Protesters describe his potential extradition to stand trial in Serbia as "unacceptable, unfair, and shameful".
Zeljko Sacic, one of the organisers of the protests, said during a rally, "Our innocent brother Purda is today in Zenica prison in solitary confinement, far away from his family and beloved ones, waiting for extradition to his hunters in Serbia."
The veterans complain that the Croatian government is not protecting them from war crimes prosecutions.
Many Croatians see war veterans as heroes and symbols of the country's fight for independence from the former Yugoslavia.
Meanwhile, Croatian police clashed with approximately 15, 000 anti-government protesters who rallied separately in Zagreb, state television reported.
According to local media reports, officers used tear gas to disperse the group on Saturday.
At least 25 people were injured, including 12 police officers and 13 citizens.
Dozens of mostly young demonstrators charged at a police cordon preventing them from reaching a central square in Zagreb, where the government headquarters is located, Croatian television reported.
The protesters threw stones and bricks at police, who responded with tear gas, the report said, adding that nearby windows were also broken.
Croatian broadcaster, RTL, also showed riot police striking anti-government protesters with their batons. Police set up metal fences to stop the crowd, the report added, describing the situation as "chaos".
Croatian police said that they detained 60 protesters because of "violent behaviour".
"Their aim was to create unrest and behave violently towards police," Tomislav Buterin, a police official, told journalists.
According to a police spokeswoman, the protesters were members of an anti-government group organised through the social networking website, Facebook, and were joined by football fans.
The protests in Zagreb came just two days after several hundred protesters clashed with police at another anti-government rally.
The demonstrators demanded the resignation of Jadranka Kosor, Croatian prime minister, over high unemployment and the country's deep economic problems.
Many Croats blame the government for the country's economic hardships and alleged corruption.
Kosor took over the helm of the government in 2009 when Ivo Sanader, her predecessor, currently detained on suspicion of corruption and abuse of power, suddenly stepped down.
Croatia's economy was hard-hit by the global crisis and has contracted for the past two years.
Mladen Pavic, a government spokesman, strongly condemned Saturday's "hooliganism and violence".
He said that "according to some information, some opposition parties were involved in organising and financing the Zagreb violence." However, he did not elaborate.
Kosor has urged an end to the protests, warning that instability could undermine Croatia's efforts to join the European Union.
President Ivo Josipovic has also appealed for the protests to remain peaceful.