The new owner of Spanish club Racing Santander, Indian businessman Ahsan Ali Syed, denied "serious allegations" over the conduct of his business.
"The source of these serious allegations is known. They are manifestly false and defamatory," said a statement by Ali and his company, Western Gulf Advisory, on its website.
Ali and his company's business practices have come under criticism in the Australian press.
They are also the object of attack by a website, http://www.westerngulfadvisory.net, which has imitated the real address of his firm, http://www.westerngulfadvisory.com.
Western Gulf Advisory, which is based in Bahrain and Switzerland, threatened legal action against anyone repeating details of the allegations.
The company released a separate press statement accusing the attack website of having sent an email attempting to extort money in return for halting the criticism.
"The email clearly seeks to extort money from myself and my companies," Ali said in the statement. "Of course, no payment was made and the consequences are there for all to see," he added.
Ali bought Racing Santander in January for an undisclosed amount but local paper Diario Montanes put the price at 30 to 40 million euros.
The club, based in the northern port city of Santander, has never won a major title in their 98-year-history.
Ali has said he wants to focus on talent, and not big names, in his quest to create a "great" club.
He guaranteed himself a friendly welcome after he announced in almost his first move as owner that tickets for his first match, against Valencia, would be free to members of the club.
The businessman made an unsuccessful 300-million-pound (350-million-euro) bid to buy English Premier League side Blackburn Rovers earlier this season.
On his company's Internet site, Ali describes himself as a legal graduate specializing in law and finance who was an advisor to "sovereign clients and high net worth individuals".
"One of the main reasons Mr. Ali started his own asset management company was that he believed in his own ability and qualifications to manage and invest his wealth," the site says.
"Absolute trust has been the bedrock of relationships at Western Gulf Advisory (WGA). A truth evidenced by Mr. Ali's mutually satisfying professional relationships with several clients in the Middle East, Europe and the Far East."
The company says it draws on the expertise of 3,200 consultants "based all across the globe".