* Guptas subject of probe that they influence Zuma
* Oakbay says all 72 transactions approved by banks
* Gordhan, at odds with Zuma, sought court ruling on Guptas
* Zuma backs Gordhan in misson to reassure investors (Adds Oakbay, Zuma quotes, details)
By Tiisetso Motsoeneng
JOHANNESBURG, Oct 18 (Reuters) - South Africa's Oakbay Investments said on Tuesday that a court application by Finance Minister Pravin Gordhan linking the firm and its owners, who have close ties to President Jacob Zuma, to suspicious transactions was flawed.
The statement comes days after Gordhan said in a court affidavit that 6.8 billion rand ($491 million) in payments made by Ajay, Atul and Rajesh Gupta and companies they control and other individuals with the same surname had been reported to authorities as suspicious since 2012.
The three Indian-born businessmen are the subject of an official investigation by the Public Protector, a constitutionally mandated anti-corruption watchdog, into allegations that they have had undue influence over Zuma. The president has denied granting undue influence to the brothers and they have denied seeking it.
Oakbay, whose chief executive, Nazeem Howa, resigned for health reasons on Monday, said all 72 transactions were approved by the banks processing them.
In a statement, the company dismissed Gordhan's application as "undiluted nonsense" and said it would provide evidence to clear suspicions about each of the 72 transactions.
It did not provide any details in the statement other than to say one of the largest payments - 1.3 billion rand from a trust account for funds dedicated to the eventual rehabilitation of an Oakbay-controlled coal mine - had been transferred from Standard Bank to Bank of Baroda because Standard Bank was closing the account.
Gordhan's submission is a request to the High Court in Pretoria for a declaratory judgment that he cannot interfere with decisions by South Africa's major banks to cut their ties with businesses owned by the Gupta brothers.
Several banks and companies have cut ties this year with Oakbay, without disclosing their reasons. They included South Africa's top four banks: Standard Bank, Nedbank, Barclays Africa's Absa and First National Bank (FNB), part of FirstRand.
Oakbay has since been using the local unit of Bank of Baroda , India's second-biggest state-run lender by assets.
A Treasury spokeswoman said the Gupta's formal response to the Oakbay statement would have to be filed in the form of an affidavit before a hearing date could be set.
Gordhan's submission on Friday capped a week of drama in which he was charged with fraud by approving early retirement for a deputy tax commissioner in 2010 and re-hiring him as a consultant. Gordhan said the fraud charge was politically motivated.
Zuma has said he supports Gordhan - looked at by nervous financial markets as a guarantor of stability - but that the law must take its course in the case against him. Gordhan supporters say the finance minister is being persecuted for his tough stance against political influence wielded by Zuma's allies.
Speaking to South African foreign service diplomats on Tuesday, Zuma said he backed Gordhan's efforts to attract investors to Africa's most industrialised country.
"It has worked very well. They have been able to go all over the world presenting South Africa," Zuma said, referring to Gordhan's charm offensive. ($1 = 14.0465 rand) (Additional reporting by TJ Stydom in Pretoria; Editing by James Macharia/Jeremy Gaunt)