"This is someone who helped make our country visible in the 1970s," government spokesman Lambert Mende said by telephone Saturday.
Ali in October 1974 won over the country's citizens before upsetting George Foreman in the capital, Kinshasa, to become heavyweight champion once again at age 32.
"This is someone who built a bridge between African-Americans and Africans," Mende said.
"He will always have an important place in the hearts of the Congolese." He said Congo's government expressed deep sympathy for Ali's family.