PRETORIA (AFP) - South African prosecutors on Monday filed an appeal calling for Paralympian Oscar Pistorius to be convicted of murder for killing his girlfriend Reeva Steenkamp.

Pistorius was jailed last year after being convicted on the lesser charge of manslaughter over the 2013 killing, and is due to be released from prison on Friday.

"What I can assure you is that today the papers were filed in the Supreme Court of Appeal," said National Prosecuting Authority spokesman Luvuyo Mfaku.

Pistorius' defence team has until Sept 17 to file its response.