Charles Ble Goude, an ally of Ivory Coast ex-President Laurent Gbagbo has made his first appearance at The International Criminal Court (ICC).
Mr Ble Goude, a former minister, has been charged with committing crimes against humanity during clashes that followed the 2010 election.
He denies all the charges - including accusations that he led a militia.
His extradition last week infuriated supporters of Mr Gbagbo, who is also at The Hague court, awaiting trial.
The warrant against Mr Ble Goude was unsealed in September.
Prosecutors at the court accused him of being responsible - "as indirect co-perpetrator" - for four crimes against humanity, including rape, murder and persecution.
The crimes are said to have been committed during between December 2010 and April 2011, following the disputed election.
Some 3,000 people lost their lives in the crisis, after Mr Gbagbo refused to concede victory to his rival, Alassane Ouattara.
Mr Ble Goude was the head of the Young Patriots, an organisation of Gbagbo loyalists that was blamed for a campaign of violence against those seen as Mr Ouattara's supporters.
In an interview last year with the BBC, Mr Ble Goude said that he had only organised rallies and meetings and never run a militia.
At the hearing on Thursday, Mr Ble Goude appeared in a grey suit with a white shirt. He confirmed his name and asserted his innocence.
"I'm a consultant in political communication," he said, greeting supporters in the gallery with a smile and a clenched-fist salute. "I will go home."
Supporters of Mr Gbagbo have described last week's handover of Mr Ble Goude to the ICC as a setback for reconciliation.
Many have accused the ICC and the government, now led by Mr Ouattara, of pursuing "victor's justice" by targeting only those who were close to Mr Gbagbo.
A UN representative overseeing human rights in the Ivory Coast issued a statement on Thursday, emphasising the need for "impartial justice for all".
"All that have committed violent crimes, whatever their political, ethnic or tribal or religious background, should be tried," Doudue Diene said.
The ICC is currently preparing to prosecute three allies of Mr Ouattara, the AFP news agency reports, quoting sources close to the court.
The Ivory Coast's next election in 2015 is expected to be a test of reconciliation in the country.