KUALA LUMPUR (AFP) - Malaysian opposition leader Anwar Ibrahim says "he's prepared for the worst" as he stares at the prospect of imprisonment once again on a controversial sodomy charge, but has vowed never to give up his struggle.

The opposition leader, whose forces won a majority of the popular vote in polls last year, faces a late-October final ruling on his appeal against a much-criticised sodomy conviction and five-year jail sentence he denounces as a long-running government smear campaign.

Opinion in Malaysia seems split on whether a regime known for its rough political tactics will risk a domestic and international backlash by throwing Anwar - infamously jailed on previous disputed sodomy charges 15 years ago - into prison again.

But the charismatic campaigner said "it doesn't look good," citing an accelerating government crackdown on civil liberties aimed at throttling the opposition threat.

"There is certainly concern that they would then use the courts to secure a (sodomy) conviction, which is really unfortunate in terms of rule of law in this country," he said in an interview at his modest Kuala Lumpur office.

Malaysia's highest court hears the appeal October 28-29.

Anwar says he is "prepared for the worst" but flashes his trademark sense of humour in speculating on the quality of the prison tea, medical care and books.

"I am thinking now of what classics to start with," he said with a laugh.

"But I am still hopeful sanity will prevail and the highest court in the land will subscribe fully to the facts and the law."

It's a case of deja vu for 67-year-old Anwar, once a rising star in the ruling United Malays National Organisation (UMNO) and its presumed future leader.

He was ousted in a 1998 power struggle and jailed for six years on earlier charges of sodomy - later overturned - and corruption, which were widely seen as trumped-up.

The episode triggered huge anti-government protests and a tectonic political shift that now has the formerly invincible UMNO reeling.

Anwar has led a once-hapless opposition to increasing electoral gains, seizing 52 percent of the popular vote in May 2013 polls by campaigning against UMNO corruption and heavy-handed rule.

UMNO, in control since 1957, retained power due to a parliamentary system skewed in its favour, prompting Anwar to decry a "stolen" election.

The latest charge that Anwar sodomised a young male aide emerged in 2008. Sodomy is illegal in Muslim-majority Malaysia.

Anwar was acquitted in 2012, but in March a higher court overturned that, sparking allegations of UMNO interference. The United States government said the decision raised concerns over rule of law.

Analysts believe UMNO deeply fears an opposition win will open the lid on decades of corruption, while influential Islamic conservatives fear the opposition alliance's pluralist promises.

Prime Minister Najib Razak's government, which denies manipulating the case, runs the risk of street protests and spooking investors if Anwar is jailed again.

"He may be found guilty, but they let him avoid jail somehow," said James Chin, a Malaysia researcher at Singapore's Institute for Southeast Asian Studies.

"The international price would be too high to pay and he would become a martyr, a big symbol for the opposition. I think they want to just keep harassing him." The government may be content to let the opposition destroy itself.

The multi-ethnic Pakatan Rakyat ("People's Pact") opposition alliance includes Anwar's diverse party, a Chinese-dominated one, and a conservative Islamic party. Festering disputes exploded this year in a bitter row over control of a key state.

Pakatan nearly unravelled, and Anwar's image as all-important unifier was diminished.

He admits "great challenges" ahead in mending fences and breaking UMNO's hold on its king-maker vote bank: the Muslim ethnic Malay majority.

Pakatan also is under mounting pressure from Najib's regime.

Dozens of opposition figures and activists, including Anwar, have been targeted with sedition charges this year for criticising the government, a clampdown condemned by rights watchdogs, including UN human rights experts.

With political speech under close scrutiny, Anwar is coy on whether Pakatan will take to the streets if he is jailed, saying the alliance has no plans but that citizens have "the right to do what it takes to defend freedom, democracy, and rule of law".

Amid concerns for his health in prison, Anwar said he has received overseas asylum offers.

"I was given that option in 1998. I rejected it," he said. "My struggle is here."