The convicted killer of a South African anti-apartheid leader was stabbed in prison ahead of his release on parole after serving a life sentence.

South African prison authorities said on Tuesday that the 69-year-old Polish man Janusz Walus was stabbed, allegedly by a fellow inmate. Walus had been convicted of killing Chris Hani, an opponent of South Africa's apartheid government. 

Correctional services department spokesman Singabakho Nxumalo said Walus' condition was stable and that he was receiving medical attention.

Why is the timing controversial?

Walus' stabbing comes only days after a ruling by South Africa's Constitutional court ordering his parole.

In a unanimous judgment, Constitutional Court Chief Justice Raymond Zondo said last week that Walus should be placed on parole within the space of 10 days.

Walus "was convicted of a very serious crime... cold blooded murder," said Zondo. The chief justice said that "his conduct nearly plunged this country into civil unrest," but he was legally entitled to parole.

The South African government also announced that he would be granted an exemption for residence in the country, in order to serve his parole and avoid deportation to Poland.

Walus' South African citizenship was revoked in 2017 when he was imprisoned.

How was the parole judgment met?

Many South Africans openly rejected the Constitutional Court's decision to grant Walus parole.

Solly Mapaila — leader of the South African Communist Party (SACP), which is part of a political alliance with the ruling African National Congress (ANC) — expressed his dissatisfaction with the decision, describing it as "apartheid injustice."

Hani's widow Limpho Hani, also expressed her anger, telling local news station eNews Channel Africa that "Chief Justice Zondo has failed this country completely," before angrily saying the decision was "diabolical."

Walus, an anti-communist Polish national, gunned down Hani in the driveway of his home in Boksburg, east of Johannesburg in 1993.

The murder came at a time when negotiations to end apartheid were reaching a critical phase and threatened to thrust the country into civil conflict.

In the immediate aftermath of Hani's killing,  then-ANC President Nelson Mandela made an impassioned plea for calm in a televised address.

rmt/sms (AFP, AP, Reuters)