Fallen Paralympic idol Oscar Pistorius is being "treated like royalty" inside prison where he is serving time for killing his girlfriend Reeva Steenkamp, according to a prison official.

South African news site Eyewitness News reports that staff are coddling Pistorius because they fear the PR fallout from anything negative happening to the former athlete.

An unnamed official for Correctional Services inside the prison also said the paralympian gold medallist shuns contact with fellow inmates by spending most of his time alone.

He reportedly spends a lot of time keeping in shape by working out using equipment lent to him by another prisoner.

Pistorius, 28, is serving five years for the manslaughter of his partner Steenkamp on Valentine's Day in 2013.

He has so far spent four months behind bars and could be released to serve the remainder of his sentence under house arrest within months.

But prosecutors have lodged an appeal in the hope of convicting Pistorius of murder, which could see him jailed for life.