Former South African Communist Party leader Chris Hani was allegedly assassinated for fear he would expose former Defence Minister Joe Modise’s involvement in the multi-million rand arms deal, said arms deal critic Terry Crawford-Browne at the Seriti Commission of Inquiry on Wednesday.

Crawford-Browne has made a number of allegations in his testimony at the inquiry established to investigate allegations of fraud and corruption in the R70 billion arms deal in 1999.

Crawford-Browne testified that there were allegations that when Hani was assassinated in 1993, he was on the verge of exposing former defence minister Joe Modise’s involvement in, and corruption relating to, the arms deal.

"It has been alleged that Mr Janusz Walus was ultimately employed by the [British arms manufacturer] BAE, perhaps by way of John Bredenkamp, the Rhodesian/Zimbabwean who was the second-largest recipient of those BAE bribes," he told the inquiry.

He said blaming Clive Derby-Lewis for Hani's murder was merely a red herring to blame white right-wing elements, diverting attention from the British arms industry.

Derby-Lewis was convicted of conspiring to kill SA Communist Party general secretary Chris Hani by providing the gun Polish immigrant Walus used to kill him in the driveway of his home in Boksburg, on the East Rand, on April 10, 1993.

The 78-year-old former Conservative Party MP, who was sentenced to 25 years behind bars, has served more than 20 years of his sentence.

Derby-Lewis was initially sentenced to death, which was commuted to life imprisonment when the death penalty was abolished in 1995. He has been repeatedly denied parole.

Modise was poisoned, the commission also heard.

"I was told by Bheki Jacobs six weeks before Mr Modise died that he was being poisoned, and that his death would be ascribed to cancer," arms deal critic Terry Crawford-Browne told the inquiry's hearings in Pretoria.

"Mr Modise was known to have many enemies and it is also known there was considerable animosity between him and Mr Chris Hani dating from their times in exile."

Bheki Jacobs, also known as Uranin Vladimir, Hassan Solomon, and Hassan Osman, died at his mother's home in 2008 after a six-month battle with cancer.

Crawford-Browne said Jacobs was an African National Congress functionary, trained in the Soviet Union as an intelligence operative.

In 2003, Jacobs was arrested, and later exonerated, for allegedly plotting an assassination. The charge of conspiring to commit murder was watered down and finally dropped.

At the time, Jacobs reportedly believed his one-time comrade and later nemesis, Mo Shaik, to be behind his surprise arrest. They had both been involved in the ANC's intelligence structures in the early 1980s.

On Wednesday, Crawford-Browne said Jacobs told him that an investigating team's report into the arms deal was being doctored pending Modise's death "so that dead men can tell no tales".

"I have now consequently reported the allegations of poisoning to the deputy commissioner of police in the Western Cape, but no action was taken," he said.

The commission was appointed by President Jacob Zuma three years ago to investigate alleged corruption in the arms procurement deal.

The government acquired, among other hardware, 26 Gripen fighter aircraft and 24 Hawk lead-in fighter trainer aircraft for the air force, and frigates and submarines for the navy.