An ex-girlfriend of Paralympic champion Oscar Pistorius has told a court in Pretoria that the athlete cheated on her with Reeva Steenkamp.

Samantha Taylor has been giving evidence on day five of Pistorius's trial, where he is accused of murdering girlfriend Reeva Steenkamp, who was shot dead through a bathroom door in the athlete's home on Valentine's Day last year.

While at the stand, Ms Taylor revealed that Pistorius was unfaithful twice, with the relationship finally ending when he began dating Steenkamp.

During proceedings, the defence highlighted emails, which they believe prove that the claims of the 27-year-old's former girlfriend are false.

Ms Taylor broke down in tears when asked about the relationship ending, which caused the court to adjourn briefly.

Pistorius has denied murdering Steenkamp and maintains that he mistook the South African model for an intruder when he fired the gunshots.