Oscar Pistorius’s trial has began with discussion of when Reeva Steenkamp may have eaten her last meal.

Witness Christina Lundgren, an anaesthetist, described when a stomach is likely to be emptied after eating.

She said the prosecution’s argument that Steenkamp’s stomach would have been empty if she ate when Pistorius said she did was “pure speculation”.

Pistorius denies intentionally killing Steenkamp on February 14 last year.

The South African Paralympic sprinter says he accidentally shot her through a toilet door in a state of panic, mistaking her for an intruder.

Pistorius had said Steenkamp ate her last meal the evening before she was killed, and that the couple had been sleeping before waking in the early hours.

The prosecution has argued that this cannot be true as Steenkamp had food in her stomach at the time of her death.

Speaking on Thursday, Prof Lundgren, who was shown copies of the post mortem report, said there were many factors that could have delayed gastric emptying in Ms Steenkamp’s stomach, including sleep, exercise, medication, and her age.

“In an ideal world, after six hours of fasting after [the] meal her stomach should probably have been empty. But there are so many unknowns about possible factors that might have delayed gastric emptying,” she said.

“One cannot state it as being fact” that Ms Steenkamp’s stomach would have been empty six hours after eating, Prof Lundgren said. “I would say it is purely speculative.”