The Ijok by-election on Saturday has big implications for both the government and former deputy prime minister Anwar Ibrahim, who is making a political comeback.

Anwar's leadership of the opposition campaign marks the first time he has returned in force to Malaysia's political scene since his sacking nine years ago by former Prime Minister Dr Mahathir Mohamad.

He is still barred from standing for public office himself.

The fight for Selangor's semi-rural Ijok seat - about 50km northwest of Kuala Lumpur - pits the ruling Barisan Nasional coalition against the opposition Parti Keadilan Rakyat, formally run by Anwar's wife.

Voting follows a rough-and-tumble campaign that saw scuffles between the rival camps, and allegations by Anwar that police stopped some of his rallies.

Police denied the allegation and said they would send in 1,000 reinforcements ahead of the vote. Roadblocks were set up to secure the area.

"For BN, this is the most serious electoral contest since its clean sweep at the 2004 general election, for the simple reason that Anwar is now spearheading the opposition," said Yang Razali Kassim, of the S Rajaratnam School of International Studies at Singapore's Nanyang Technological University.

"A one-time prime minister-in-waiting is now leading the charge against the BN. If there is any erosion of support, it will signal future problems for the BN and embolden the opposition," he told AFP .

A tough fight

Both the BN and Keadilan see the Ijok ballot as a key test ahead of general elections expected well before they must be held in 2009.

"There is no doubt it is a tough fight," said political analyst Mohammad Agus Yusoff from the Universiti Kebangsaan Malaysia.

BN is more likely to win "as they have a formidable machinery and they are more focused," he predicted.

"But in terms of people attending the gatherings and talks, Keadilan managed to pull crowds with their highly-charged speeches and rhetoric."

Mahathir fired Anwar after he faced sodomy and corruption charges that landed him in jail for six years.

Anwar's sodomy conviction was later overturned but the corruption verdict still stands, barring him from standing for public office until April 2008.

Anwar said he believes a national vote will be called prior to April, to prevent him from running.

The ban did not stop him from winning fans as he spoke to various ethnic groups last weekend. He called for a "war on poverty" and alleged rampant corruption under the BN, led by Prime Minister Abdullah Ahmad Badawi's Umno.

The MIC, part of the BN coalition, is fielding K Parthiban, 38, as its Ijok candidate against Keadilan's Khalid Ibrahim, 61.

BN defeated Keadilan by 1,649 votes in the last state election in 2004.

Star power

Keadilan is hoping to use Anwar's star power to gain support for the party, whose profile has declined since its creation in the wake of his 1998 sacking from government.

"It will energise Keadilan. It is the biggest challenge for us and if we win then we will be able to move forward," Khalid told AFP .

Ijok was once an agricultural-based constituency surrounded by vast rubber and oil palm estates but many of the town's younger people now work in factories outside the area.

A state lawmaker's death earlier this month precipitated the by-election in the constituency of 12,372 voters, a little over half are Malays.

After the announcement of the poll, new street lamps and traffic lights sprung up while narrow, potholed roads were being widened and freshly tarred in a place normally regarded as a backwater.

Yang Razali predicted BN will win with a narrow victory but said a narrow loss was "not an impossibility."

But he said it would take more than a defeat in Ijok to halt Anwar's political comeback.

Mohammad Agus agreed and said BN would have to accept that Anwar has returned.

"The underlying message is that Anwar is back in politics. This is a good signal for BN leaders to think of how to overcome this challenge, whether or not Keadilan wins."