Oscar Pistorius is being sued for compensation by the parents of his late girlfriend Reeva Steenkamp, it has emerged, on the day before he appears in court to be charged with her murder.

Steenkamp would have turned 30 on Monday. Instead, the day will see Pistorius, 26, charged with her premeditated murder, prosecutors in Pretoria confirmed. He is likely to go on trial early next year.

Steenkamp's parents, June and Barry, are suing Pistorius, claiming their daughter's death deprived them of the financial support they were relying on for their old age.

Pistorius denies murder, claiming he shot Steenkamp by mistake, believing she was an intruder after she hid in the bathroom of his home.

Barry Steenkamp, 69, and his wife June, 66, said they were of modest means, and depended on their daughter for financial help. Reeva, a model and TV personality, bought their food and paid their bills, they said.

Pistorius, who became the first Paralympian to compete against able-bodied athletes in the 400 metres at the London 2012 Games, has earned millions through sponsorship and advertising deals.

"We have no choice but to sue," said June Steenkamp, in answer to criticism that she was seeking money from the man who killed her daughter.

"Pistorius has placed us in this position. We are struggling financially - Reeva helped us."

June Steenkamp said that on the day Reeva died, she had promised to pay the couple's cable TV bill.

"I was fretting that I would miss her first TV appearance," said June. "She told me not to worry, that she would send money."

Steenkamp's former boyfriend Warren Lahoud, whom she saw two days before her death, is expected to give evidence at the trial.

June Steenkamp said her daughter rowed bitterly and often with Pistorius, but never with Lahoud.

Pistorius was granted bail of 1m rand (£64,000), and is living with his uncle, Arnold Pistorius.