Israeli regulators say one of the country's wealthiest businessmen has been questioned on suspicion of securities fraud.

IDB Holding Corp. notified the Tel Aviv Stock Exchange on Tuesday that its chairman, Nochi Dankner, was questioned about the alleged offenses. Dankner said in a statement that his activities were lawful.

"The Israel Securities Authority is looking into the matter," Dankner said. "I respect the investigation process and have full confidence in the ISA. I am convinced that it will soon be found that all my actions, in all matters, were and will always be lawful and performed honestly without fault."

The ISA said in a statement to a court that Dankner was questioned with two associates on suspicion of fraud, breach of trust and money laundering. He was banned from leaving the country.

The ISA suspects that Dankner and his associates sought to influence the share price of the troubled company by carrying out millions of dollars' worth of fraudulent transactions.

"This is truly an earthquake," a senior official in Israel's capital market said.

IDB Holding, made up of some of Israel's largest companies, is struggling to pay its huge debts.