The official opposition DA asked her, as it has most ministers, how much she and certain senior officials had spent on hotels and restaurants since April this year.

"The costs were according to the rules and the ministerial handbook," she replied, without giving the details requested.

Mthethwa, the minister of police, was forced by similar questions to reveal that he had spent more than R800000 on hotels since December.

Ian Davidson, the DA chief whip, said he would raise the minister's refusal with Max Sisulu, the Speaker of parliament.

Parliament's website mentions the right to demand answers from cabinet ministers as a cornerstone of South Africa's democracy.

Dlamini-Zuma's spokesman said that the minister had "answered the question to the best of her ability, but if the DA want further information there is nothing to stop them asking for it".