Malaysian opposition leader Anwar Ibrahim proclaimed his innocence when he finally took the witness stand Monday at his long-running sodomy trial.

Testifying in his own defense, Anwar insisted he has never had sexual relations with the 26-year-old former aide who is his chief accuser. Anwar described his prosecution as a “vile and vicious” attempt to destroy his reputation.

Anwar's lawyers had sought to have the case dismissed but a judge ruled in June that the prosecution case was credible. The trial was postponed earlier this month to allow Anwar's lawyers to interview potential witnesses, including Prime Minister Najib Razak.

The former aide says he spoke to Mr. Razak before Anwar was charged.

If convicted, Anwar faces 20 years in prison. He was previously jailed on an earlier sodomy charge but that conviction was overturned by a higher court.

Anwar's party made major gains in Malaysia's last parliamentary elections. The next election is expected sometime next year.