Robert Grace Mugabe zimbabwe
President Robert Mugabe kisses his wife and first lady Grace Mugabe during during the country's 37th Independence Day celebrations at the National Sports Stadium in Harare April 18, 2017. EKESAI NJIKIZANA/AFP/Getty Images

Granted diplomatic immunity by South Africa, the wife of Zimbabwean President Robert Mugabe returned home from Johannesburg on Sunday despite calls that she be prosecuted for allegedly assaulting a young model at a luxury hotel there.

Zimbabwean state broadcaster ZBC showed Grace Mugabe greeting government and military officials at the Harare airport after returning on an Air Zimbabwe plane with her husband, who had attended a summit of southern African leaders in Pretoria. The Mugabe couple did not attend a state funeral for a senior ruling party official later in the day in the Zimbabwean capital; the president usually presides over such events.

South Africa's foreign minister, Maite Nkoana-Mashabane, granted immunity to Grace Mugabe in a government gazette notice that was published Sunday. Signed on Saturday, the notice recognizes "the immunities and privileges of the First Lady of the Republic of Zimbabwe, Dr. Grace Mugabe."

South African police had previously issued a "red alert" at borders to ensure she didn't leave undetected and had said they were waiting for a government decision on the immunity appeal.

The country's main opposition party, the Democratic Alliance, called for a parliamentary inquiry into South Africa's decision to let the Zimbabwean first lady leave and said on Twitter that the government has "no more legitimacy in the arena of international diplomacy and displays a total disregard for the rule of law."

John Steenhuisen, a senior opposition official, compared the South African handling of the Mugabe case to the government's decision to allow Sudanese President Omar al-Bashir to leave the country in 2015 even though he was wanted by the International Criminal Court for alleged war crimes, the African News Agency reported.

Gabriella Engels, a 20-year-old model, said Grace Mugabe attacked her on Aug. 13, whipping her with an extension cord that cut her forehead.

In reaction to the news that Mugabe had returned to Zimbabwe, a group representing Engels said Sunday it would go to court to challenge the South African government over the immunity issue.

"We will take a long-term approach on this," said Willie Spies, legal representative at AfriForum, an organization that primarily represents South Africa's white Afrikaner minority.

"She may be back in Zimbabwe, but it may mean that she will find it very difficult to come back to South Africa in the future," Spies said.

Zimbabwe's state media have largely remained silent on the scandal over Zimbabwe's first lady.

The Zimbabwean president's outspoken wife has been criticized for a fiery temper and lavish shopping expeditions, but her rising political profile has some asking whether she is maneuvering to succeed her husband. She recently said that Zimbabwe's ruling party should restore a provision in its constitution stating that one of the party's vice presidents should be a woman, and has publicly challenged her 93-year-old husband to name a successor.

Also Sunday, one of Zimbabwe's two vice presidents, Phelekezela Mphoko, presided over the funeral for Shuvai Ben Mahofa, a senior member of Zimbabwe's ruling party who died a week ago.

South African Airways, meanwhile, said Sunday — hours after the Mugabes returned to Harare— that it was resuming flights between South Africa and Zimbabwe after they were blocked by Zimbabwean authorities.

Zimbabwe's action on Saturday followed the grounding of an Air Zimbabwe flight at Johannesburg's main international airport on Friday evening. That plane was cleared for flying on Saturday night, South African civil aviation authorities said. It was unclear whether the Mugabes used the same aircraft to return to Zimbabwe.

Both countries said they had imposed restrictions because the affected planes did not have a "foreign operator's permit."

South African Airways said it prepared and submitted required documents after the cancellation of flights between Johannesburg, Harare and the Zimbabwean city of Victoria Falls.

The airline dispute had nothing to do with political tensions linked to the scandal over Grace Mugabe's alleged assault, Zimbabwe's transport minister, Joram Gumbo, told state media.

Willie Spies, the lawyer representing the model who said she was assaulted, speculated that the airline impasse was a Zimbabwean ruse designed to distract attention from the first lady's troubles.