The now-36-year-old became the first double amputee to compete at an Olympic Games in the men's 400 metres and as a member of South Africa's men's 4x400 metres relay squad at London 2012, and he won six Paralympic gold medals from Athens 2004 through to the Games in London.

However, the sprinter's career ended in disgrace when he murdered Steenkamp at their home in Pretoria on Valentine's Day in 2013, firing four times through the bathroom door.

Having initially been convicted of culpable homicide in 2014, this was upgraded to a six-year sentence for murder in 2016, increased to 13 years and four months by the Supreme Court of Appeals the following year.

South African law dictates that offenders must have served at least half of their sentence before becoming eligible for parole, but in Pistorius' case there was confusion on when should be deemed the start.

The Correction Services Department (DCS) in March said he had not served enough time to qualify for release, but the Constitutional Court overturned that decision and deemed he passed the halfway mark on March 21 this year.

Tania Koen, representing Steenkamp's parents, agreed with the ruling, commenting "as it was our view that Oscar Pistorius was eligible to be considered for placement in March 2023", as reported by South Africa's News24.

DCS spokesperson Singabakho Nxumalo acknowledged the Constitutional Court ruling.

"The Department of Correctional Services has received an order from the Constitutional Court on the proper interpretation of the Supreme Court of Appeal's judgment [on Pistorius' sentence] delivered on 24 November 2017," Nxumalo told News24.

"Briefly, the matter relates to the sentence given to inmate Oscar Leonard Pistorius, its effective date and the impact on the calculation of the minimum detention period.

"DCS is studying the order and shall in due course pronounce itself on the way forward.

"This shall ensure that the order of Court is correctly executed."