Sport Minister Fikile Mbalula must tell Parliament how much his department spent on its trip to London, the DA said on Friday.
"We are particularly interested in hearing whether the state footed the bill for Julius Malema's stay in the luxurious Corinthia Hotel in London," Democratic Alliance MP Winston Rabotapi said in a statement.
"The DA will not rest until we know how much of the people's money minister Mbalula has spent on this trip."
Earlier, Mbalula denied claims that he or the sport department footed the bill for Malema's London stay.
Rabotapi said Parliament was still awaiting answers to questions on how funding from the National Lottery and private sponsorships for the Olympics was used. It was also waiting to hear how many officials from the department were attending the games.
He said Mbalula had a tendency to spend public money on parties and junkets.
"Last year, his department spent R45.9-million on the annual sports award ceremony, with R8-million coming from the National Lottery Board (despite being earmarked for Olympic athletes) and R12.1-million from the department of sports and recreation," said Rabotapi.
"Responses to DA questions on ministerial flights revealed last year that Minister Mbalula and his deputy have spent a combined total of over R2.6-million on 345 domestic and international flights since 1 April 2010."
He said the sport department had a R36.9-million budget for travel and subsistence.
The DA was also interested in the costs relating to the Ekhaya Hospitality Centre, an intergovernmental initiative spearheaded by the department.
"The department is reportedly refusing to disclose information on the costs involved in the running of the centre and the various entertainment acts that will be staged there over the next six weeks," said Rabotapi.
Parliamentary questions should help determine how funding allocated to athletes compared to that spent by government officials at the Olympics.
"Minister Mbalula must prove to us that our athletes' performance is his top priority," said Rabotapi.