Tens of thousands of supporters cheered Malaysia’s opposition figurehead Anwar Ibrahim last weekend as he launched his bid for a by-election expected to return him to parliament.

The Aug. 26 ballot in Anwar’s home state of Penang is being seen as a test of his popularity after a young male aide accused him of sodomy – the same charge that saw him jailed a decade ago.

"I am touched by the support. This is an overwhelming support," Anwar said as he arrived at the nomination centre in the Permatang Pauh constituency which was locked down by barricades and an armed security presence.

Some 30,000 supporters shouted Anwar’s battle cry of "Reformasi", and waved party flags, facing off against 5,000 government supporters to trade taunts and insults.

At least 3,000 police including the riot squad were deployed to keep the peace, and a police helicopter hovered overhead.

"We want change. The future is Anwar. Long live Anwar!" chanted supporters of the opposition leader, a former deputy premier who was sacked in 1998 and convicted on sodomy and corruption counts widely seen as politically motivated. The sodomy conviction was later overturned.

"I am so moved by the villagers who came out so early in the morning to show their support," Anwar said as he prepared to formally register for the byelection, escorted by family members, opposition allies, and his lawyers.

Anwar, 61, has said the sodomy allegations were fabricated to prevent him from ousting the ruling Barisan Nasional coalition, after March elections that handed the opposition alliance a third of parliamentary seats.

He was formally charged earlier this month, just after his wife vacated the Permatang Pauh constituency – which she has held since he went to jail – to allow him to return to parliament after a decade-long absence.

Anwar, representing his Keadilan party, is running against Arif Shah Omar Shah, a veteran member of the United Malays National Organization (UMNO) which leads the ruling National Front coalition.

A two-term state legislator whose ability to speak Mandarin and the local Hokkien dialect is a plus in the multi-racial seat, he is nevertheless considered the underdog in a district Anwar held from 1982-1999.

In a racial breakdown that broadly mirrors the national population, more than two-thirds of voters in Permatang Pauh are Muslim Malays. Chinese make up 26 per cent and Indians make up six per cent.

"I have known the people here and they know what to expect from me if I am elected. I am after all a two-term assemblyman and I have been doing my work since way back," said Arif.