Israeli police on Monday detained diamond magnate Beny Steinmetz and four others as part of an international money laundering investigation, authorities said.
Tal Silberstein, an adviser to Austrian Chancellor Christian Kern, was also among those detained, as was the acting chairman of Israeli telecommunications firm Bezeq.
It was the second time Steinmetz had been detained by Israeli authorities since December, when he was placed under house arrest as part of a corruption probe involving mining deals in the African nation of Guinea.
Besides the Guinea investigation, the Israeli billionaire was charged in Romania last year with forming an organised criminal group and money laundering in a property-related case that cost the state $145 million.
Israeli police said five suspects had been detained on Monday morning for questioning on suspicions including money laundering, fraud, forgery, obstruction of justice and bribery.
Homes and offices were also searched.
The suspects were not named in the statement, nor were details provided on where the alleged offences may have occurred.
However, police later said those detained included Steinmetz and Silberstein.
Both men appeared in a magistrates court later Monday in Rishon Lezion near Tel Aviv and had their remands extended until Thursday.
Kern's Social Democrats issued a statement saying they will no longer work with Silberstein "after the legal accusations that have emerged out of Israel today".
Silberstein has also worked as an adviser to former Israeli prime minister Ehud Olmert.
Bezeq said its interim chairman David Granot was also detained for questioning, but added that the investigation did not involve the company.
Israeli police said they were "investigating a number of suspects since the morning on suspicion that they worked systematically with the main suspect in order to produce and present fictitious contracts and transactions, including in the field of real estate in a foreign country, for the purpose of money transfers and money laundering".
The investigation was being conducted with "international cooperation", they said.
Steinmetz controls mining firm BSG Resources and has a net worth estimated by Forbes of $1.02 billion, making him the 17th-richest person in Israel.
In December, he was ordered to remain under house arrest until January 2.
At the time, BSG Resources issued a statement calling the allegations against Steinmetz "baseless".