Zimbabwe's government has sought diplomatic immunity for President Robert Mugabe's wife in the assault case against her in South Africa, South Africa's police ministry has said.
Grace Mugabe was still in South Africa, it added, contradicting earlier reports that she had returned to Zimbabwe.
A 20-year-old South African model has accused Mrs Mugabe of assaulting her at a hotel in Johannesburg on Sunday.
Police expected Mrs Mugabe, 52, to turn herself in on Tuesday, but she did not.
Zimbabwe's government had invoked "diplomatic immunity cover" for her, the ministry said in a statement.
However, South Africa still wanted to make sure that she was "processed through the legal system", the ministry added.
Discussions were taking place with Mrs Mugabe's lawyers and the Zimbabwean High Commission over the issue, it said.
Appearing before a parliamentary committee earlier, South Africa's acting police chief Lesetja Mothiba said that Mrs Mugabe "must go to court".
She has not commented since police began investigating her over the alleged assault.
South Africa's government risks a public backlash if it lets Mrs Mugabe go scot-free.
This happened in 2015, when it failed to execute an international arrest warrant for Sudan's President Omar al-Bashir who was wanted by the International Criminal Court.
South Africa's government argued that he qualified for diplomatic immunity, but the country's judges disagreed. The government was then strongly criticised for undermining the rule of law.
It seems that the government wants to avoid a similar backlash and is therefore insisting that Mrs Mugabe must appear in court.
But by taking such an approach it risks a diplomatic row with Zimbabwe's government - a staunch ally whom it has resolutely defended over the years despite international criticism of President Robert Mugabe's human rights record.
So the two governments are bound to be in talks to resolve the crisis over Mrs Mugabe.
One option being mentioned in the South African media is that Mrs Mugabe should plead guilty during a short court appearance, and pay a fine.
But it is unclear whether Mr and Mrs Mugabe - known for their uncompromising nature - will agree to this, especially after Zimbabwe's ruling Zanu-PF party said in a tweet on Tuesday that the first lady was "attacked", contradicting the version of her accuser.
Zimbabwe's main opposition party, the Movement for Democratic Change (MDC), said the first lady was a "total disgrace and a complete national embarrassment".