Defeated PKR Hulu Selangor by-election candidate Zaid Ibrahim today filed a petition to invalidate the election result, claiming widespread bribery was perpetrated in his opponent's campaign.

The petition was filed on the grounds that the BN candidate P Kamalanathan had directly or indirectly known about offers made by Prime Minister Najib Abdul Razak during the campaign, to entice Hulu Selangor voters to cast their ballots for the ruling coalition.