An international bank has been charged with assisting Antwerp diamond dealers to hide money in offshore accounts to evade tax.

According to multiple media reports, the Belgian prosecutor has charged a Switzerland-based subsidiary of HSBC Bank, HSBC Private Bank SA (Suisse), with fraud and money laundering.

In a statement, the prosecutor alleged that the bank “knowingly eased and promoted fiscal fraud” by allowing clients to move money into offshore companies based in Panama and the Virgin Islands.

The prosecutor claimed that the bank’s activities – which were estimated to have cost the Belgian government hundreds of millions of euros – dated back as far as 2003 and involved soliciting and managing the assets of more than 1,000 wealthy clients, mainly from the Antwerp diamond industry.

HSBC reportedly acknowledged in a statement that a formal investigation was underway by both Belgian and French authorities as to whether the bank had acted appropriately in the past with regards to a number of its clients that had tax-reporting requirements in the two countries.

The statement added that HSBC would “continue to co-operate to the fullest extent possible”.

Antwerp has long been considered a global diamond-trading hub. It is believed that approximately 1,700 diamond companies are registered with over 4,500 diamond dealers in the Belgian city.