Cape Town — Grace Mugabe returned home to Zimbabwe with her husband, President Robert Mugabe, on Sunday without having to appear in court on charges of assaulting a woman in a Johannesburg hotel room.

The Zimbabwe Broadcasting Corporation reported on Sunday that the First Lady was part of an official delegation to a Southern African Development Community leaders' summit which landed at Harare International Airport in the early hours of Sunday.

At the time she left, she was facing charges of whipping across the face a young South African model she found in a South African hotel frequented by her sons. The incident took place a week ago.

Controversy swirled around Mugabe all last week as:

• South Africa's police minister announced that she would appear in a Gauteng court on assault charges but she failed to make an appearance;
• South African government sources told journalists both that the Zimbabwean government had invoked diplomatic immunity, and that government lawyers had said she did not qualify;
• Later reports quoted a government source as saying immunity would be recognised - but the South African foreign ministry said no decision had been made.

An announcement that immunity would be recognised could have given rise to a court challenge to prevent Mrs Mugabe from leaving the country pending an application to have the immunity revoked. There was an outcry two years ago when the government facilitated Sudanese President Omar al Bashir's escape from South Africa while a court was hearing an application to have him arrested on a warrant issued by the International Criminal Court.

The model's lawyer has vowed to "fight this matter to the highest court", suggesting that if South Africa recognises immunity, he will seek to overturn it - raising the prospect of Mrs Mugabe being unable to return to South Africa, at least until the issue is resolved through the courts.

The lawyer is Gerrie Nel, the prosecutor who had athlete Oscar Pistorius jailed on charges of killing his girlfriend. Nel works for a newly-established private prosecution agency set up in the wake of accusations that government prosecutors allow influential political leaders and businessmen - including President Jacob Zuma and his friends - to escape justice.