KUALA LUMPUR, Malaysia – Dressed in black as a symbol of mourning, thousands of Malaysians gathered on Wednesday (May 8th) to denounce elections which they claim were stolen through fraud by the coalition that has ruled for 56 years, AFP reported.

The rally was called by opposition leader Anwar Ibrahim, who has vowed a "fierce" campaign for electoral reform after losing Sunday's vote. He says he has 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.

Meanwhile, 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.