Christchurch, March 22 NZPA - A man will say he punched a woman in the head because she bit him during oral sex, a Christchurch District Court jury trial has been told.

The man's account of a series of encounters - he faces serious assault and sex charges arising from the incidents - was put to the woman as she was cross-examined by defence counsel on the first day of the trial.

Richard John Keepa, 33, denies the woman's account of being knocked unconscious with a push into a concrete wall, being detained and sexually violated, and being strangled twice.

The woman spent most of the day in the witness box giving her evidence and being cross-examined by defence counsel Tony Garrett.

She said an argument had developed in a car as the pair were being driven to their homes after a night out drinking in Christchurch. Mr Garrett said Keepa would say she punched him and she spun into the concrete fence as he pushed past her.

He accused her of making up another incident after that.

The man would deny that she had ever been threatened with bolt-cutters, after her earlier account that he had threatened to cut off her fingers.

Mr Garrett said the man's evidence would be that he punched her head when she bit him during oral sex.

He would say that rather than detaining the woman, he had restrained her because she assaulted him.

The trial, before Judge Jane Farish and a jury, is expected to take four days. The crown is calling evidence from 30 witnesses.

Keepa has pleaded not guilty to 12 charges: wounding with intent to cause grievous bodily harm, two of intentionally injuring the woman, threatening to kill her, unlawful detention with intent to have sex, assault with intent to commit sexual violation, threatening to do grievous bodily harm, sexual violation, indecent assault, attempted sexual violation, assault, and possession of an offensive weapon.