The Unified Communist Party of Nepal-Maoist Chairman was heading towards Belauri to address a rally ahead of the Constituent Assembly polls on November 19. No one was injured by the blast, police said.
Bombs were also found near the venue where Prachanda was scheduled to address the closing ceremony of his party's Mechi-Mahakali National Campaign, the Himalayan Times reported.
The attack came a day after an army bomb disposal team defused an improvised explosive device planted merely 100 m away from a dais from which Prachanda and former premier Baburam Bhattarai were to address an election rally at Kanchanpur.
Meanwhile, police rounded up at least a dozen CPN-M activists from Chitawan district in southern Nepal for trying to enforce a transport strike.
A 33-party alliance, headed by the Communist Party of Nepal-Maoist, a breakaway faction of UCPN-M, is boycotting the crucial polls. This is Nepal's second national election since a 10-year civil war ended in 2006.
More than 100 parties, including the three major ones - the Unified Communist Party of Nepal-Maoist, the Nepali Congress and the Madhesi Jana Adhikar Forum, are fielding candidates for the 601-seat assembly, which will draft a new Constitution.
People's POWER: How the world chooses its FUTURE