Following an order issues by an investigating judge, police raided HVIDRA offices in Zagreb to prevent journalist Domagoj Margetic to show a recording with President Stjepan Mesic's testimony at the Hague tribunal in the association's offices.
Margetic has been indicted by the UN war crimes tribunal in The Hague for publishing in the press a testimony of a protected witness.
Spokesman for the Interior Ministry Zlatko Mehun said Pandza and Jurendic resisted arrest, so the police had to use force.
Zagreb police issued a statement saying that Margetic was presented with the court warrant earlier on Monday.
Attorney Krasnik told reporters on Monday evening he was outraged with the fact that he has to react by defending people like Pandza.
"They used force against a disabled person who lost his leg in the Homeland Defence War," Krasnik said, adding that the rule of law no longer existed in Croatia.
HVIDRA premises are private property and nobody can enter them without a court order, the attorney said.
Police violated the Constitution and a number of law and physically abused HVIDRA members, Krsnik said.
Pandza claims he had not resisted the arrest and that he asked to see the warrant which the police had not shown.
He said one police officer told him he had a warrant and dragged him outside where four policemen tied his hands behind his back, threw him on his knees and beat him,
"I asked if I was arrested, they said no but that I had to go with them," Pandza said.
He said he was then taken to hospital to get an x-ray of his ribs given that he was complaining about chest pain. After the x-ray showed that nothing had been broken, Pandza was taken to the Crnomerec police station where, as he claims, he was offered to sign a statement which contained untruths. He declined to sign it.
Pandza said that Jurendic, who did not appear at Monday evening's news conference, "had it even worse".