Swazi King Mswati’s royal house has been rocked by a new sex scandal in which his wife, Nothando Dube, was allegedly caught having sex with his close ally, justice minister Ndumiso Mamba.

The minister and the queen were arrested on Tuesday night at a luxury hotel, the Royal Villas, at Ezulwini outside Mbabane.

Sources said Mamba was initially detained at Mafutseni police station, outside Manzini, on Tuesday, questioned on Wednesday and then moved to Big Bend prison. This was on the orders of the king, who also instructed that the matter be kept secret and that the minister be kept in jail until the king returned from a 10-day state visit to Taiwan.

There were fears that if they were freed the two could flee the country. Mswati left on Sunday.

Although there is no formal charge against Mamba, a City Press source said yesterday that the queen mother had on Friday dispatched a delegation to the minister’s own king in his village to lay charges of “trespassing into another man’s home”.

The practice is called “ukubeka icala” – laying a charge. By yesterday, sources in Mbabane said Mamba was still incarcerated and efforts to contact him were futile. Swazi media houses were warned that authorities were aware that they were working with South African media on the story.

They fear that their lines are bugged. Dube, known as LaDube, is not the first Mswati wife to wander. In 2004 two of Mswati’s wives – Delisa Magwaza (LaMagwaza) and Putsoana Hwala (LaHwala) – fled the royal palace as news of infidelity spread across the kingdom, Africa’s last absolute monarchy.

LaMagwaza, who now lives in London, fled to Cape Town as news of her steamy relationship with a young Soweto lover, Lizo Shabangu, hit the headlines. Shabangu took the story of their secret romance to The Sunday Times after LaMagwaza ended the affair.

LaHwala was forced out of the palace amid allegations of infidelity and fled to Alexandra township in Johannesburg, where she lived with her family. She is believed to be in Soweto.

In Swaziland, where newspapers are banned from reporting on royal scandals, and where opposition political parties are banned, people live in fear of the kingdom’s authorities and speak in low, hushed tones about the sex scandals of the royals.

The latest scandal has been kept under wraps all week. Nobody wants to talk on record, but City Press has confirmed the incident with at least four independent sources. Bheki Dlamini, the CEO in Mswati’s office, declined to comment yesterday.

“I am in Taiwan and I am not aware of the arrest of the justice minister in Swaziland. Please contact the police commissioner in Swaziland,” he said.

Police commissioner Isaac Magagula also declined to comment yesterday, insisting the minister had not been arrested. “I do not know anything about it. The police have nothing to do with it. I deal with crime here. No one I know has been arrested. I know nothing.”

When told some royal sources had confirmed it, Magagula quipped: “So why are you coming to me? I do not know anything. Please leave me alone.” Government spokesperson Macanjana Motsa could not be reached for comment.

Mamba’s father was envoy to London and Mamba grew up in the family of the king. Mamba is unlikely to get bail because of Mswati’s dictatorial power. The queen – the 12th of Mswati’s 14 wives – is being held under 24-hour surveillance at the queen mother’s royal palace at Ludzidzini in Mbabane while waiting for the king to return.

Usually, new wives are kept with the king’s mother at Ludzidzini while suitable accommodation is sought for them and while they are being inducted into royal life. Truant wives are also banished there.

Mamba, a personal friend of the king, signs investment deals for Mswati, his wives and children.

The arrest is set to rock the royal household to the core and rattle the South African royal family of King Goodwill Zwelithini. The Zulu king is married to one of Mswati’s sisters and to one of her nieces, Zola Mafu. Mswati is also close to President Jacob Zuma, who paid lobolo for one of the Swazi royal’s cousins, but never married her.

LaDube (22) first caught the roving eye of the king when she was a 16-year-old finalist in the Miss Teen Swaziland beauty pageant in 2004.

She married him on June 11 the following year after he spotted her at the annual uMhlanga (reed dance) ceremony on August 30. LaDube is a year younger than Mswati’s first child, Princess Sikhanyiso. Mamba, one of the king’s most trusted lieutenants, was appointed to the Senate in 2009 and promoted to minister a week later.

He had to quit as MD and CEO of royal-owned Tibiyo Taka Ngwane, the small kingdom’s biggest and most powerful private investment institution.