The accident occurred at Rama bend, between Purola and Mori, about 110-km from Uttarkashi, said Purola SDM RK Pandey.
Singh, who received injuries to his feet and hands, was airlifted in a chopper to Dehradun for treatment, added Pandey.
The accident took place around 11 A.M. When the minister for food and civil supplies was on his way to Purola to address a meeting of Congress workers, which was subsequently called off, party sources said.