KUALA LUMPUR: Thousands of Malaysians dressed in mourning black gathered Wednesday to denounce elections which they claim were stolen through fraud by the coalition that has ruled for 56 years.
The rally was called by opposition leader Anwar Ibrahim, who has vowed a "fierce" campaign for electoral reform after losing Sunday's vote and has said he would soon produce evidence of fraud by what he calls an "illegitimate" government.
Prime Minister Najib Razak's Barisan Nasional (National Front) coalition government has hotly denied the opposition's numerous allegations of cheating.
It also denounced the gathering in a 25,000-seat stadium on the outskirts of the capital Kuala Lumpur.
In a statement, the coalition said Anwar has "deliberately chosen a small stadium to ensure it will spill onto the streets. His protest is calculated to create unrest."
Previous election reform protests have ended in wild scenes, with police using tear gas and water cannon. Police had earlier threatened to arrest participants in Wednesday night's rally.
But with tension high over the country's closest-ever election result, police backed off and a festive atmosphere prevailed as rally-goers waved opposition party flags and blared vuvuzela horns.
"I think they should redo the election," said university student Tan Han Hui. "I'm here to support democracy. I feel the election is so unfair and there are so many dirty tricks."
Participants filled the stadium's stands and spilled onto the football field.
Anwar has battled Barisan since he was ousted from its top ranks in 1998 and jailed for six years on sex and corruption charges widely seen as trumped-up. He says the election was stolen via "unprecedented electoral fraud".
Anwar, who was due to address the gathering later in the evening, has called on Malaysians across the country to wear black in protest.
Among other allegations, voters complained that indelible ink -- meant to thwart multiple voting -- easily washed off. Accounts of suspected foreign "voters" being confronted by angry citizens at polling centres went viral online.
Anwar had alleged a government scheme to fly tens of thousands of "dubious" and possibly foreign voters to flood key constituencies.
The government has poured scorn on the allegations. But a report released Wednesday by two independent watchdogs said the polls were marred by pro-government bias and irregularities that indicate "serious flaws" in the electoral system.
The Institute for Democracy and Economic Affairs and Centre for Public Policy Studies cited concerns including partisan use of government machinery, pro-government media bias and doubts over the integrity of voter rolls.
The election was "only partially free and not fair", the report said.
The vote was touted as the first in which the opposition had a chance to unseat the ruling coalition, which has governed since independence in 1957.
Barisan retained a firm parliamentary majority despite winning less than half the popular vote, a factor blamed on gerrymandering and Barisan tinkering with electoral districts.
Police originally said the rally was illegal as organisers did not give authorities the required 10 days' notice.
On Wednesday they said it could go ahead but warned participants could face subsequent legal action for any "seditious" speech.
Both the United States and European Union congratulated Najib on his win but urged him to address reports of irregularities.
Anti-graft watchdog Transparency International said in a statement the vote showed that electoral reforms were "urgently required".
Suspicion over the result could cause an extended period of unrest, according to Joshua Kurlantzick, a Southeast Asia Fellow with the Council on Foreign Relations in Washington.
"Anger is going to simmer for weeks or months, and is already growing fiercer on Malaysia's free online media," he wrote in an analysis.