"Raja has been suspended with immediate effect from the party due to his continuous anti-party activities," Assam Pradesh Congress Committee President Bhubaneswar Kalita said in a statement here.
Raja was earlier removed from the post of party general secretary on AICC directives.
Kalita urged all partymen to remain united and disciplined to confront the political challenges being faced by Congress.
Raja had lost the 2009 Lok Sabha polls as a Congress candidate from Nowgong.