Oscar Pistorius formally appeals against murder conviction for killing Reeva Steenkamp

Oscar Pistorius has launched a formal appeal against his conviction for murdering his girlfriend Reeva Steenkamp.

The South African athlete killed Ms Steenkamp on Valentine's Day in 2013 after firing multiple times through a locked bathroom door.

He was convicted of murder last month after a previous manslaughter charge was overturned.

Pistorius has now applied to South Africa's Constitutional Court in a last-ditch attempt to avoid another prison sentence.

Pistorius, 29, could face a minimum 15-year jail term if his appeal fails.

He was released from prison - having served just one year of a five-year sentence - in October to live under house arrest at his uncle's property in Pretoria.