South African officials were on Friday considering whether to grant diplomatic immunity to Zimbabwe's first lady Grace Mugabe over her alleged assault on 20-year-old model in a Johannesburg hotel.

Mugabe, who has not been seen since the Sunday's incident, is due to attend a Southern African Development Community (SADC) meeting in Pretoria this weekend along with her husband President Robert Mugabe.

The first lady claimed immunity after allegedly whipping Gabriella Engels with an electrical extension cord at a Johannesburg hotel where Mugabe's two sons, both in their 20s, were staying.

"The correspondence from the government of Zimbabwe is being given consideration," Nelson Kgwete, spokesman for the foreign ministry, told AFP.

The Mugabes will join other heads of state and their spouses at the two-day meeting in the South African capital starting Saturday.

Engels -- who has registered a case of assault with intent to cause grievous bodily harm -- appeared at a press conference on Thursday, wearing a large plaster on her forehead.

Her lawyers told reporters she had been offered cash to make the incident "go away" but that she had refused and was determined to press charges against Mugabe.

Willie Spies, one of the lawyers, said that if diplomatic immunity was granted they "would consider bringing an urgent application to the high court to prevent the decision from being executed".

- Grace expected on duty -

Grace Mugabe, 52, was in South Africa reportedly to have her ankle treated following a minor accident last month.

President Mugabe, 93, flew into the country late Wednesday, the day after his wife failed to attend an agreed meeting with South African police over the hotel incident.

The SADC summit in Pretoria opens at 09:30 am (0730 GMT) on Saturday, with a "first spouses programme" starting at noon. A closing ceremony on Sunday afternoon is also scheduled to include partners of the heads of the states.

Zimbabwean officials have declined to comment either on the allegations against the first lady or her immunity claim.

South African police have said they are on high alert to prevent Grace Mugabe leaving the country.

Grace and Robert Mugabe's two sons Robert Jnr and Chatunga live in Johannesburg, where they have a reputation for partying. The couple also have an older daughter who lives in Zimbabwe.

Although South Africa and Zimbabwe have strong political and economic ties, this incident threatens to strain relations between the two neighbours.

Grace Mugabe regularly speaks at rallies in Zimbabwe and is seen as one potential successor to take over from her increasingly frail husband.

In 2009, she was granted diplomatic immunity in Hong Kong after she repeatedly punched a British photographer for taking pictures of her at a luxury hotel.

Source: AFP