A South African court has issued an interim order preventing Sudanese President Omar al-Bashir from leaving the country.
It says Mr Bashir will have to stay until the court hears an application later on Sunday on whether he should be handed over to the International Criminal Court (ICC) in The Hague.
Mr Bashir is in Johannesburg for an African Union (AU) summit.
He faces ICC war crimes and genocide charges over the Darfur conflict.
The ICC has called on South Africa to arrest him. However he was welcomed by South African officials when he arrived in Johannesburg on Sunday.
There are tensions between the ICC and the AU, with some on the continent accusing the court of unfairly targeting Africans.
The AU has previously urged the ICC to stop proceedings against sitting leaders.
The warrants against Mr Bashir, who denies the allegations, have severely restricted his overseas travel.
He has, however, visited friendly states in Africa and the Middle East.
The ICC has issued two arrest warrants against Mr Bashir. The court relies on member states to carry out arrests.
However correspondents have said the South African government – a signatory to the treaty establishing the ICC – is unlikely to move against the Sudanese leader.
The AU has previously refused to co-operate with the ICC, accusing it of bias against African leaders.