Swiss authorities have decided to provide Belgium with judicial assistance in its investigation of two Belgians accused of dealing in conflict diamonds, The Associated Press Reports.

Belgium alleges that five Geneva-based firms used fake certificates to import raw diamonds worth $525 million, the AP reports. The diamonds were then sold to Belgians suspected of having made payments contributing to the funding of warfare in African countries.

Switzerland’s highest court rejected appeals from the Geneva firms to block the transfer of documents and bank records to Belgian authorities, the AP reports. The rulings by the Swiss Federal Tribunal were released Oct. 10.

Belgium is also investigating whether fictitious business deals were made through Geneva to evade taxes, according to the rulings.

The Swiss tribunal did not release the names of the companies, the AP reports.

JCK