The Paralympic star was jailed for five years in 2014 for the culpable homicide of Reeva Steenkamp.

Ms Steenkamp's parents have said that the time he has served is "not enough for taking a life".

A state appeal against his acquittal on murder charges is due in November.

Under South African law, Pistorius is eligible for release under "correctional supervision" having served a sixth of his sentence.

Murder charge sought

The double amputee shot and killed Ms Steenkamp through a locked bathroom door at his Pretoria home, believing she was an intruder, he told his trial.

In March a Johannesburg court blocked his legal team's attempts to stop the prosecutors' appeal.

State prosecutors say Pistorius should have been found guilty of murder - if convicted he could face a much more lengthy jail term.

Pistorius was born without the fibulas in both of his legs, and had surgery to amputate both below the knee while still a baby.

He went on to become one of South Africa's best-known sports stars, and was the first amputee to compete against able-bodied athletes at the 2012 London Olympics.