The family of Oscar Pistorius have criticised the media for sensationalist coverage of the murder case against him.

Henke Pistorius, 59, the South African Olympic and Paralympic star's father, said he was "very disappointed" by weekend press reports that a blood-stained cricket bat was a vital piece of evidence in the killing of the athlete's girlfriend, model Reeva Steenkamp.

"I'm disappointed in the integrity of some of the newspapers," Henke told the Guardian.

Pistorius, known as the Blade Runner because of his hi-tech artificial legs, is due back in court for a bail hearing on Tuesday morning.

"I'll be sitting behind Oscar," said Henke. "We will split the rubbish from the fact. This is a very bad matter. It is an accident. Out of respect for Oscar, I don't want to say anything else."

Asked if he found the media reports sensationalist, he replied: "Of course. That's their job. They want to sell newspapers."

British newspapers have not escaped criticism for their coverage of the case, with the Sun's front page – featuring a big picture of Steenkamp in a bikini – prompting hundreds of complaints, including from the former deputy prime minister Lord Prescott.

Pistorius repeatedly broke down in tears in a Pretoria court last Friday. His father and brother, Carl, were sitting behind him and leaned forward at different times to put comforting hands on his back. His sister Aimee was also present.

Pistorius, 26, has been held in a police cell since 29-year-old Steenkamp was found shot dead at the athlete's home last Thursday. Police reportedly check on him hourly.

At Tuesday's hearing, Pistorius's defence team is expected to present its case first, arguing that their client is not a danger to the public and does not pose a flight risk. It will also be the first opportunity for the prosecution to describe evidence police gathered against the double-amputee runner and why they are pushing for a charge of premeditated murder. Police have said they will oppose his bail application.

Hundreds of miles away in Port Elizabeth, Steenkamp's family are preparing for her funeral, also on Tuesday. A private ceremony at a local crematorium is planned, closed to the public and media.

"We're just taking things one day at a time," Steenkamp's brother Adam was quoted as saying by the Associated Press (AP). "But at the moment it's family coming together and the one person who would be the strongest, who held us all together, is unfortunately not here anymore and that's my sister."

Steenkamp's mother paid tribute to her daughter. June Steenkamp told the Times of South Africa: "Why? Why my little girl? Why did this happen? Why did he do this?

"Just like that she is gone. In the blink of an eye and a single breath, the most beautiful person who ever lived is no longer here.

"All we have is this horrendous death to deal with … All we want are answers … answers as to why this had to happen, why our beautiful daughter had to die like this."

Pistorius's family deny he committed murder, though they have not addressed whether he shot her. South African media reports suggest that Pistorius claims he mistook her for an intruder in his home.

In an email to AP on Monday, Pistorius's longtime coach said he believed the killing was an accident. "I pray that we can all, in time, come through this challenging situation following the accident and I am looking forward to the day I can get my boy back on the track," Ampie Louw wrote.

"I am still in shock following the heartbreaking events that occurred last week and my thoughts and prayers are with both of the families involved."

Louw said Steenkamp had often accompanied Pistorius to training. "I found her to be delightful, very friendly... and I found the two of them to be very happy in each other's company."