Johannesburg (AFP) - A South African court ruled Thursday that a Polish immigrant who shot dead the anti-apartheid hero Chris Hani in 1993 should be released on parole after 23 years behind bars.

Janusz Walus, 63, is serving a life sentence for the murder, which took the country to the brink of a race war and sent shockwaves across the world.

"The court has ordered (Walus) be released within 14 days and the matter be referred back to the parole board to set his parole conditions," Walus's lawyer Julian Knight told AFP.

But the ruling African National Congress, in power since the end of apartheid in 1994, called the judgement a "travesty of justice" and said Walus should be sent back to Poland.

"(Hani's) death robbed our nation of a committed revolutionary who embodied the undying resolve to freedom and liberation," the party said in a statement.

"The African National Congress demands that Janusz Walus is immediately deported to his country of origin on his release, never to return to South Africa."

A supporter of the extreme right-wing movement, Walus immigrated to South Africa from then-communist Poland in 1981.

According to Knight, he is now a South African citizen.

- 'A watershed moment' -

Hani was the general secretary of the South African Communist Party (SACP) and chief of staff of Umkhonto we Sizwe, the armed wing of the ruling African National Congress (ANC).

He was shot dead in the driveway of his house on April 10, 1993 in a suburb east of Johannesburg, one year before South Africa's first multi-racial elections. The incident sparked protests in black townships.

Still in negotiations with the apartheid government over an election date, then-ANC president Nelson Mandela appeared on national television to appeal for calm.

"Now is the time for all South Africans to stand together against those who, from any quarter, wish to destroy what Chris Hani gave his life for -- the freedom of all of us," he said.

"This is a watershed moment for all of us."

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The SACP said in a statement Walus was unrepentant and that it would not leave the court's decision unchallenged: "We are studying the judgement and will decide on the next course of action."

Walus's lawyer said his client was remorseful, adding: "He qualifies for release in terms of the department of correctional services' own policy guidelines."

Last year, the man who provided Walus with the gun he used to kill Hani was released on medical grounds.

Clive Derby-Lewis, 79, who is suffering from lung cancer went to court after several unsuccessful applications to the parole board.

Hani's family has repeatedly opposed the bail applications of both Derby-Lewis and Walus, arguing neither had shown no remorse since they were jailed in 1993.

One of South Africa's most notorious murderers, Eugene de Kock, was granted parole in January 2015 after 20 years in jail.

De Kock, dubbed "Prime Evil", was sentenced in 1996 to two life terms plus 212 years in prison for his activities as head of a police death squad targeting anti-apartheid activists.