Minerals and Energy Minister Phumzile Mlambo-Ngcuka rushed to the aid of her beleaguered husband Bulelani Ngcuka, firmly rejecting allegations that he was an apartheid-era spy, it was reported in Cape Town.

In a statement issued in her private capacity on Wednesday night, she said allegations made against her husband in the last few weeks have included a pending appointment to De Beers mining company, "which would clearly discredit both of us, that he has a child with a teenager, that his car was impounded by the state and the latest is that he was a spy".

The Ngcuka family rejects the spying allegations with the "contempt they deserve" but they do not intend to make "clearing Bulelani's name" a crusade and sustain the drama because "he has nothing to clear".

"During the nomination process there was a window of opportunity to bring this information to light. We find it strange that a concerned vigilant cadre of the organisation would have held back and not even tipped off the president, the minister of justice, the ANC's executive committee and its national working committee," she said.

According to former transport minister Mac Maharaj "my husband informed on the National Association of Democratic Lawyers and Hank van Handel Trust, a scholarship organisation he served on as trustee," Mlambo-Ngcuka said.

She says that Maharaj alleges that Ngcuka's spy identity was "confirmed" by the fact that Ngcuka had three identity documents "which were discovered when we applied for the birth certificate of our son Luyolo, who was born in Geneva".

Ngcuka has threatened to sue both Maharaj and City Press, which first published the spy allegations, for an unspecified amount. Documents leaked to the paper and purportedly from the National Intelligence Agency database, identify Ngcuka as possibly, but not conclusively, an apartheid police spy nicknamed "Agent RS452".

Weeks before Ngcuka announced his decision on Deputy President Jacob Zuma, an allegation appeared in the same paper that Ngcuka had improperly acquired his luxury BMW vehicle. But it later emerged that the fault lay with the justice department.

Mlambo-Ngcuka said the Ngcukas had "much more important work to do, providing services to the people of South Africa and advancing the critical work of government and the ANC, rather than wasting time on mudslinging with comrades".

With acknowledgements to Andre Koopman, Charles Phahlane and the Daily News.