KUALA LUMPUR (AFP) - Malaysia's highest court on Thursday set a late October hearing date for opposition leader Anwar Ibrahim's appeal of a controversial sodomy conviction that threatens his political career.

Anwar was convicted in March of sodomising a young former male aide, and has been sentenced to five years in prison. He says the charges are fabricated in order to halt the opposition's recent momentum.

If the appeal fails, it would be a major blow for the fractious Pakatan Rakyat (PR) opposition alliance, which united around the charismatic campaigner to achieve unprecedented gains in the past two elections.

The case also has raised fears of public protests if Anwar is sent to jail.

N. Surendran, one of Anwar's lawyers, said the Federal Court set October 28 and 29 for the appeal.

Sodomy is illegal in Muslim-majority Malaysia, even if consensual, and punishable by up to 20 years in jail.

Surendran called the case a "political conspiracy" to cripple the opposition.

"We fully expect the Federal Court to set aside the conviction. The whole world knows these are trumped-up and fabricated charges," he said.

Anwar's legal battles have gripped Malaysian politics for nearly two decades.

A one-time rising star in the ruling United Malays National Organisation (Umno), he was ousted in a bruising late-1990s power struggle, and convicted and jailed on an earlier, separate sodomy charge, which he also said was false.

In the current case, Anwar political aide Mohamad Saiful Bukhari Azlan accused the opposition leader of sodomising him in 2008. The allegation came shortly after Anwar led Pakatan to historic electoral gains that rocked the Umno establishment.

A lower court found Anwar not guilty in 2012, but an appeals court sensationally overturned that verdict in March, drawing international criticism.

Adding to Anwar's troubles, Saiful in June filed a civil lawsuit against Anwar over the sodomy case, seeking RM$50 million (S$20 million) in damages.