Former Bosnian Serb army chief Ratko Mladic was removed from the UN war crimes court at The Hague after refusing to enter a plea and disrupting the judge's attempts to read out the charges against him.
The judge later entered formal pleas of not guilty on behalf of Mr Mladic to the various charges against him, which include genocide.
The charges relate to the 43-month siege of the Bosnian capital Sarajevo and the massacre of 8,000 Muslim men and boys in Srebrenica - Europe's worst massacre since World War II.
Having threatened to boycott his second hearing since being tracked down, arrested and extradited from Serbia in May, Mr Mladic did appear, but spent several minutes demanding different legal representation and requesting a delay before having to plead.
'No, no, I'm not going to listen to this without my lawyer,' Mr Mladic shouted as he removed his translation headphones when judge Alphons Orie began reading out the charges.
'Who are you? You're not allowing me to breathe,' he said.
The 69-year-old was represented by a court-appointed lawyer.
The judge said the court would look into allowing him to be represented in future by other lawyers of his choice.
Arrested after 16 years on the run, Mr Mladic had defiantly rejected war crimes charges against him as 'obnoxious' and 'monstrous' when he was formally charged at the Yugoslavia war crimes court last month.
The stakes are high for Serbia because the trial could unearth evidence showing Belgrade knew about or helped commit genocide at Srebrenica if Mr Mladic argues he was carrying out orders, or the desires, of political leaders.
The International Court of Justice ruled in 2007 that Serbia failed to prevent genocide, but was not responsible for it. The decision shielded Serbia from compensation claims from Bosnia.
Mr Mladic, who has said he is a 'gravely ill' man, is no longer in the prison hospital and now plays chess with other detainees.
He argued last month he only defended his country and people.