|Anwar Ibrahim, pictured with wife Wan Azizah, insists the allegation is meant to sully his reputation [AFP]
Malaysia's opposition leader has dismissed sodomy charges against him, calling them a "vicious lie" meant to ruin him politically.
Anwar Ibrahim struck a defiant note as he spoke in his defence for the first time in the trial on Monday.
"The allegation is a blatant and vicious lie and will be proven so. This is a vile and desperate attempt at character assassination," Anwar told a courtroom in the capital, Kuala Lumpur, packed with journalists and foreign diplomats.
Dressed in a dark suit, Anwar read the opening statement from the dock as the defence began presenting its case in the often-delayed trial. The prosecution rested its case in March.
"This entire process is nothing but a conspiracy by Prime Minister Najib Razak to send me into political oblivion by attempting once again to put me behind bars," he said.
Anwar spent an hour reading out the statement, in which he said the prosecution's case was riven by inconsistencies.
"I categorically deny the charges against me. I want to state in no uncertain terms that I never had sexual relations with the complainant," he said.
"They can do all they want to sully my reputation and threaten me with ... jail. They won't be able to cow me. The truth will prevail."
The 64-year-old, a former deputy prime minister, is charged with sodomising a young male aide, Mohamad Saiful Bukhari Azlan, in June 2008 and faces up to 20 years in prison if convicted. Sodomy is illegal in Malaysia.
His legal battles have dominated Malaysian politics for years.
Malaysia was once one of Asia's most politically stable countries under Mahathir Mohamad, who as prime minister had groomed Anwar to lead the economically vibrant, multi-cultural nation.
But a bitter split over how to deal with 1997 Asian currency crisis led to Anwar's arrest the following year - and later conviction - on separate sodomy and corruption charges widely seen as politically motivated.
He was freed in 2004 after that sodomy conviction was overturned and sparked a resurgence by the political opposition, which achieved historic gains against the ruling Barisan Nasional in 2008 general elections.
Saiful has said he met with Najib before filing a police report on the sodomy accusation, which Anwar's defence team says indicates the case was made up.
Najib's government has denied involvement in the case and he has refused to speak to defence lawyers or be called as a witness in interviews last week ordered by the trial judge.
Anwar's appearance comes after police used tear gas and water cannon to put down a demonstration calling for electoral reform on July 9, the biggest anti-government protest in years.