KUALA LUMPUR (REUTERS) - Malaysian opposition leader Anwar Ibrahim said on Thursday he was a victim of a conspiracy but was hopeful of winning an appeal against a sodomy conviction and five-year prison term that could stymie his political ambitions for good.

Anwar was the ruling party's rising star in the mid-1990s before he fell out with then Prime Minister Mahathir Mohamad.

Since then, Anwar has been beset by legal problems and spent several years in prison after being convicted of corruption and an earlier sodomy charge.

But the charismatic Anwar, who heads a three-party opposition alliance, remains the greatest threat to Malaysia's political establishment.

"Based on the facts and the law, I see no other possibilities, no other options, except to acquit me of all these frivolous charges," Anwar told supporters outside the court after his legal team wound up their arguments.

"Clear people can see now, with the evidence of fabrication, of conspiracy, of the powers that be," he said.

On Thursday, his lawyers questioned DNA evidence.

They said a DNA sample taken from a male former political aide who in 2008 accused Anwar of sodomising him had taken 96 hours to reach a chemist and was contaminated and possibly tampered with.

The government has rejected the notion of political interference in Anwar's conviction saying Malaysia had an independent judiciary and the case was a matter for the courts.

A court convicted Anwar in March and sentenced him to five years in prison. Sodomy is illegal in Malaysia.

Malaysia's highest court began considering his appeal on Tuesday and is expected to complete the hearing early next week.

If Anwar, 67, loses the appeal he faces a return to jail and would be barred from contesting the next general election that must be held by 2018.

A ruling against him could also inflame tension after opposition gains in a general election last year when Prime Minister Najib Razak's ruling alliance recorded its worst-ever performance, raising the possibility of a genuine challenge for the ruling party that has held power in multi-ethnic Malaysia since 1957.

Lead prosecutor Muhammad Shafee Abdullah told reporters he would be setting out the full facts on Friday.

"There are always two sides to a case, that's the beauty about the law. We can answer all the issues raised," he said.

Scores of Anwar's supporters have thronged at security barriers manned by police outside the court in Kuala Lumpur this week, but there has been no trouble.

Anwar has urged them not to resort to violence and not to be provoked.

Anwar was sacked as deputy prime minister and finance minister in 1998 and then campaigned against corruption and nepotism and led a nationwide "reformasi" (reform) protest movement before he was jailed in 1999 for corruption.

In 2000, he was convicted of sodomy for the first time. The conviction was overturned in 2004 and Anwar was released from prison and returned to head a revitalised opposition.