Zimbabwe’s first lady, Grace Mugabe, has denied assaulting a South African model in a hotel suite in Johannesburg last month, saying she acted in self-defence after being attacked with a knife.

In a previously unreported deposition from 17 August, Mugabe countered the version of the incident given by Gabriella Engels to police and media.

According to Mugabe, she was protecting herself after intervening on behalf of her adult sons, Chatunga and Robert Jr, who were “in trouble with a drunken young woman”.

The statement said Mugabe, 52, was considering seeking attempted murder charges.

Engels alleges an irate Mugabe burst into the room in a luxury hotel where she was waiting with two friends to meet Chatunga Mugabe on 13 August and started beating her with an electric cable.

Photographs taken soon after the incident showed a gash to Engels’ forehead and head.