Convicted murderer and former Paralympic runner Oscar Pistorius is heading back to court in an effort file a lawsuit against the South African authorities and to convince them to hold a parole hearing for him.

The former Paralympic gold medallist is serving a 13-year sentence for killing his girlfriend Reeva Steenkamp in 2013.

Pistorius shot Steenkamp through a locked bathroom door, claiming he mistook her for a burglar.

His lawyer Julian Knight  confirmed that his client was seeking an order to force authorities to hold a parole hearing, Seeking an early release over a dispute about when his sentence started.

A series of challenges and rulings by the Supreme Court of Appeal (SCA) has led to confusion about when his sentence became effective.

Pistorius argues that he has already served enough time in prison to be eligible for parole, and therefore authorities should look at whether he can be released early.

In 2017, the supreme court of appeal said that Pistorius should serve 13 years and five months for the murder of Miss Steenkamp – overturning a previous, more lenient punishment of six years for murder.

Last year, the same court ruled that his current term should be backdated to october 2014, when he was initially sentenced for a lesser charge of culpable homicide.

Pistorius argues that this backdating means he became eligible for parole in February last year.