Malaysian opposition leader Anwar Ibrahim has been formally charged with sodomy against a former male aide, BBC reported.
Appearing in court in Kuala Lumpur, Mr Anwar pleaded not guilty and called the accusation "malicious".
He has said the allegation is politically motivated. The 60-year-old was jailed after facing similar accusations 10 years ago.
Since his release he has been active in politics but, until recently, not able to officially run in elections.
Mr Anwar arrived at the main court in Kuala Lumpur amid chaotic scenes.
Dozens of supporters gathered as he emerged from his car - some shouting "reformasi", the slogan of the movement he founded.
In court, Mr Anwar was charged with "carnal intercourse against the order of nature".
Sodomy is illegal in Malaysia and he could face up to 20 years in jail if convicted.
After Thursday's hearing, he was released on bail.
Mr Anwar led the new opposition coalition to strong gains in a general election earlier this year, and had said the claims are aimed at derailing his political revival.
The accusation is the same as the one he faced in 1998 - after he had been sacked as deputy prime minister.
He was convicted and served six years before the guilty verdict was overturned.
The BBC's Robin Grant in Kuala Lumpur says a recent opinion poll suggests that few Malaysians believe Mr Anwar committed the crime.
Mr Anwar has accused Prime Minister Abdullah Badawi of orchestrating a campaign against him - Mr Abdullah has denied this.
The charges was made just as Mr Anwar prepared to fight for a seat in parliament, after a ban on his seeking public office expired.