Oakbay Investments, which is controlled by President Jacob Zuma’s friends the Gupta family, has demanded finance minister Pravin Gordhan withdraw a court application implicating the company in “suspicious transactions”, a day after welcoming the chance to prove its innocence.

Oakbay said Gordhan should withdraw the application for a court to rule that he has no obligation to intervene in a decision by the country’s largest banks to shut Gupta-controlled company accounts, as Oakbay has asked him to do.

The legal process would mean spending “taxpayers’ money in a reckless and inappropriate manner”, Oakbay’s lawyers said on Tuesday in a letter to Gordhan’s attorneys.

In his affidavit last week, Gordhan attached an annex from the Financial Intelligence Centre, a corruption watchdog, that implicated family members and their businesses in 72 alleged suspect transactions totalling R6,8bn. Oakbay said on Tuesday all the activities in question were approved by the banks that handled them.

The Guptas, who are in business with Zuma’s son, Duduzane, have been investigated by the nation’s graft ombudsman over allegations that they have wielded undue influence over government appointments and contracts. The family and the president deny wrongdoing. Zuma has sought a court interdict to prevent the publication of the results of the probe.