JOHANNESBURG (Reuters) - South African police have put a “red alert” on the country’s borders to prevent any attempted flight by Zimbabwean first lady Grace Mugabe, who is accused of assaulting a model in a Johannesburg hotel with an electric cable.

FILE PHOTO: President Robert Mugabe and his wife Grace greet supporters of his ZANU (PF) party during a rally in Harare, Zimbabwe, May 25, 2016. REUTERS/Philimon Bulawayo/File Photo

Her 93-year-old husband, President Robert Mugabe, is also in South Africa for a regional summit, complicating the diplomatic dilemma confronting Pretoria, which already has a difficult relationship with its troubled northern neighbor.

South Africa is home to an estimated three million Zimbabweans who accuse Mugabe of trashing a promising African democracy but Pretoria has been powerless to prevent Zimbabwe’s economic and political decline over the last two decades.

Grace Mugabe, 52, has asked for diplomatic immunity in the case but has not been charged. Her whereabouts were not known on Thursday although police minister Fikile Mbalula said she remained in the country.

The alleged victim, 20-year-old Gabriella Engels, has accused Mugabe of barging into a hotel room on Sunday where Engels was waiting to meet one of Mugabe’s sons, and whipping her with an electric extension cable.

Mugabe had been due to appear in court on Tuesday afternoon under a deal struck with authorities but failed to turn up, police said.

On Thursday, Mbalula said a “red alert” had been issued to South African border posts to prevent Grace Mugabe fleeing.

“We had already put tabs on the borders, in relation to her leaving the country, so there’s no question about that,” he said. So far she had made no attempt to flee, he added.

The South African government has made no official comment on the case and foreign ministry spokesmen have not answered their phones for two days but the issue is causing waves at the highest level.

Justice Minister Michael Masutha told Reuters he was attending a meeting on Wednesday evening to discuss the matter but declined to give details.

Police have said Grace will get no special treatment, and Engels’ mother, Debbie, is cranking up the public pressure, including releasing graphic pictures of her daughter’s head injuries that required 14 stitches.

On Thursday, it emerged that she had also enlisted the legal help of Gerrie Nel, the former state prosecutor who secured a murder conviction against track star Oscar Pistorius.

At a news conference, Nel said the Engels family had been offered cash to drop the case but had turned it down.

“It’s not about money. It’s about justice,” he said.

Nicknamed “The Pitbull” for his combative style in the blockbuster Pistorius trial, he also said detectives had told Engels they were seeking an arrest warrant for Mugabe.

“DIPLOMATIC IMMUNITY”

However, a senior police source said Nel was jumping the gun because of Mugabe’s application for diplomatic immunity.

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“We are not preparing an arrest warrant yet,” the source said. “Our investigations were completed but before we could take the next step, the suspect applied to invoke diplomatic immunity. We are waiting the outcome before we can move on to the next step.”

Mugabe came to South Africa for medical treatment to an injured foot, almost certainly invalidating her claims to diplomatic immunity, legal experts said.

However, given the potential diplomatic fallout, prosecutors could decide not to pursue the case if they thought the injuries to the alleged victim were not too severe, criminal attorney Riaan Louw said.

Harare has made no official comment and requests for comment from Zimbabwean government officials have gone unanswered.

A lawyer identified to Reuters as Mrs Mugabe’s representative declined to answer any questions. Zimbabwe’s ambassador to Pretoria, Isaac Moyo, did not answer his phone.

Reporting Robert Mugabe’s visit to South Africa, Zimbabwe’s Herald newspaper, the government’s main mouthpiece, made no mention of the controversy swirling around his wife, which puts Pretoria in a diplomatic bind.

Mugabe is seen by many Africans as the continent’s elder statesman and a hero of its anti-colonial struggles but Nelson Mandela accused him in 2008 of a “tragic failure of leadership” and Mugabe’s relationship with President Jacob Zuma has been testy at times.

For Debbie Engels, the only issue is getting Grace Mugabe to face the law.

“She had an electric cord wrapped around her hand and she started attacking them. She hit my daughter with a plug socket,” Engels told Reuters. “I just want justice for my daughter. It’s not about money. It’s about justice.