(b) " State transport undertaking" means any undertaking providing road transport service, where such undertaking is carried on by,-
the Central Government, or a State Government;
any Road Transport Corporation established under section 3 of the Road Transport Corporations Act, 1950 ; (64 of 1950 .) 2[
any municipality or any corporation or company owned or controlled by 3[ the Central Government or one or more State Governments, or by the Central Government and one or more State Governments].