Updated

About 20,000 Malaysian opposition supporters gathered in the capital Saturday demanding the resignation of the country's Election Commission in the wake of contentious polls.

The opposition claims bias by the commission cost them a historic win against Malaysia's 56-year-old ruling coalition and has filed petitions challenging results in some areas, claiming fraud.

The rally in central Kuala Lumpur was the 15th since the May 5 elections, in which the Barisan Nasional (National Front) clung to power despite losing the popular vote in its worst showing ever.

"We have won the elections," opposition leader Anwar Ibrahim told the crowd.

"So we will continue our protests in parliament and outside."

The rallies had raised the spectre of political instability but fears have ebbed as the opposition has tempered its demands after initially refusing to accept the results.

Turnout on Saturday was far lower than opposition officials had predicted, perhaps in part due to a recent spike in pollution from forest fires in nearby Indonesia that also has blanketed Singapore.

"The momentum is dying down," rally participant Faisal Ooi, 55, told AFP.

The government, led by Prime Minister Najib Razak, has rejected charges of cheating. Ruling party figures accuse Anwar of risking instability out of sour grapes over the election result.

Parliament opens Monday and the opposition has said it will not boycott.

The opposition says voter rolls for May's elections were full of irregularities. Supposedly indelible ink introduced by the Election Commission to prevent multiple voting also easily washed off.

Barisan developed Malaysia's economy over the decades but many analysts say the country is losing its competitive edge. The opposition has blamed corruption and repressive tactics by Barisan, and pledged to free up society and improve governance.

The opposition says the Barisan-constructed electoral system unfairly favours the ruling bloc.

Anwar points to the May 5 polls -- in which the opposition won the popular vote, but Barisan won more seats thanks to the layout of constituencies -- as proof.