The party alleged that the attempt was made when Singha, a member of its Central Committee, was headed to a rally in Kinnaur in the state. It said that the act was aimed at suppressing the workers' struggle.
Singha escaped with minor injuries in the alleged attack, CPI(M) said in a statement here.
The vehicle used in the attack, along with the persons in it, were later apprehended by local people, it said.
"CPI(M) strongly condemns the attempt on the life of Rakesh Singha, Central Committee member of the party in Himachal Pradesh.
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The party said Singha is leading a struggle of the workers who are on strike at a hydroelectric project built by a private company.
"This heinous attack was obviously planned in order to suppress the workers' struggle," the party said.
According to reports, the workers of the project have been agitating against the company, which they allege has been flouting labour laws.
Singha, who was supporting the agitation, had recently said that the conflict was the outcome of sheer "injustice" meted out to the natives who had not received the compensation due to them from the company.