Two men convicted in the assassination of civil rights icon Malcolm X are set to be exonerated after spending decades maintaining their innocence.

Muhammad Aziz, now 83, and the late Khalil Islam were convicted in 1966, after a trial in which authorities withheld evidence favourable to the defence, said their lawyers, the Innocence Project and civil rights lawyer David Shanies.

Manhattan District Attorney Cyrus Vance Junior’s office is expected to join the men’s lawyers on Thursday in asking a judge to throw out the convictions.

Malcolm X was killed on February 21 1965, at the Audubon Ballroom in Harlem, New York, as he was beginning a speech.

Aziz, Islam and a third man, Mujahid Abdul Halim – also known as Talmadge Hayer and Thomas Hagan – were convicted of murder in March 1966 and sentenced to life in prison.

Muhammad Aziz is set to be cleared after more than half a centuryMuhammad Aziz is set to be cleared after more than half a century (AP)

Hagan said he was one of three gunmen who shot Malcolm X, but he testified that neither Aziz nor Islam was involved.

For decades, the two said they were innocent and offered alibis and no physical evidence linked them to the crime.

Malcolm X gained national prominence as the voice of the Nation of Islam, speaking about the importance of black people claiming their civil rights “by any means necessary” in his highly visible role with the Black Muslim organization.

But he later split with the group and, after a trip to Mecca, started speaking about the potential for racial unity.

It earned him the ire of some in the Nation of Islam, who saw him as a traitor.

Aziz was released in 1985, Islam was released two years later and died in 2009. Both continued to press to clear their names.