Belgian police raided the offices of state bank Belfius on Tuesday as part of a probe into possible tax avoidance by companies exposed in the Panama Papers, the 2016 global investigation into the offshore industry led by the International Consortium of Investigative Journalists.

Belgian media reported that the Dec. 5 raid follows last year’s revelations that Belfius’ former subsidiary, Experta Corporate and Fund Services, had been a prominent client of Mossack Fonseca, the Panamanian law firm at the center of the Panama Papers probe based on 11.5 million leaked files.

Experta, a tax consulting firm, helped to establish hundreds of offshore companies on its clients’ behalf, allegedly taking advantage of lax reporting requirements for foreign accounts, according to the Belgian news organizations Le Soir, Knack and De Tijd.

The ICIJ and its media partners revealed that Experta requested the Panamanian law firm set up 1,659 offshore entities for clients in Belgium, France and Germany. Most of the companies have since closed.

Experta, whose services range from accounting and tax advice to financial planning, according to its website, was a unit of Dexia Group — the Franco-Belgian bank later renamed Belfius — until 2011. That year Experta was sold to Banque Internationale à Luxembourg.

The leaked files also showed that dozens of private meetings took place between Experta and Mossack Fonseca lawyers between 2002 and 2011, Knack reported. Directors of Dexia, the former parent bank, included Belgium’s ex Prime Minister Jean-Luc Dehaene, and authorities are now investigating what role the bank’s managers played in the tax avoidance schemes.

The raid at the Brussels headquarters of Belfius signals that, after months of investigation by the federal police anti-fraud unit, Belgian authorities have begun to close in on the most active players in the offshore advisory business.

Since the ICIJ and its media partners published the Panama Papers in April 2016, at least 150 inquiries in more than 70 countries have been announced, and governments around the world have investigated more than 4,500 taxpayers and companies, according to ICIJ estimates.

On Tuesday Belgian officers seized computers and files documenting Dexia and Experta’s business operations, De Tijd reported. A Belfius spokeswoman told local media that the bank is cooperating with the investigation.

In the aftermath of the Panama Papers revelations, politicians criticized Experta for enabling tax avoidance, and possibly helping clients hide funds, even after its former parent Dexia had been rescued by a $3.7 billion government bailout in 2008.

“It is inconceivable for a financial institution, which has been supported by taxpayers money, to become involved, actively or passively, in tax evasion on such a scale,” said Finance Minister Johan Van Overtveldt last year, according to Belgian media.