Kuala Lumpur: Malaysia's Anwar Ibrahim rejoined parliament on Thursday after a 10-year absence and immediately clashed with the government he aims to oust, leading an opposition walkout.

Anwar, once the protege of former Prime Minister Mahathir Mohamad, was forced from office in 1998 on corruption and sodomy charges he says were part of a conspiracy to ruin his career.

"I feel vindicated. I feel great that I am back," Anwar told reporters after he was sworn-in and appointed opposition leader, the day before the government unveils its 2009 budget that is widely expected to contain populist spending measures.

Ten years since he was last in parliament, Anwar is being backed by the biggest number of opposition MPs in Malaysia's history in his quest to oust the Barisan Nasional coalition that has ruled the country for the past 50 years.

At the same time Anwar must fight new sodomy charges, which he says are politically motivated.

He clashed with the government over a bill that will require suspects in criminal cases to submit DNA samples - a measure he fears could be used against him after he refused to give DNA in the new sodomy case, arguing it could be tampered with.

Anwar led a walkout of opposition MPs and the bill was passed at the second reading by the government MPs, making its passage into law a formality.

"We staged a walkout, there is no point in staying in and participating. This is very disappointing, the government remains in a state of denial," Anwar told reporters.