At least 40,000 Malaysian opposition supporters are rallying at a stadium to protest what they say are fraud-marred election results that enabled the long-ruling coalition to cling to power.

Opposition leader Anwar Ibrahim's three-party alliance believes the National Front coalition used illegal voters, bogus ballots and other irregularities in May 5 national polls to extend its 56 years of rule. Prime Minister Najib Razak has rejected the accusations and maintained that the elections were free and fair.

The National Front won 133 of Parliament's 222 seats, but Anwar's alliance plans to mount a legal challenge against the results of at least 30 seats.

Opposition supporters filled a sports stadium Wednesday night for a rally marking the start of a campaign to demand more electoral transparency.