(Reuters) - An investigating magistrate has been appointed in Belgium after Democratic Republic of the Congo in December filed criminal complaints accusing Apple ( AAPL ) subsidiaries of using so-called conflict minerals in their supply chain, a lawyer for Congo said Monday.

"I can confirm that the Belgian investigating judge has been appointed," said Leo Fastenakel, one of the lawyers representing the Congolese government in Belgium.

"We believe he is a serious and rigorous judge," he added, without naming the magistrate.

Any decision on whether or not offences have been committed will be based on an investigation carried out by the investigating magistrate, another lawyer on the case told Reuters in December.

Congo is a major source of tin, tantalum and tungsten, so-called 3T minerals used in computers and mobile phones. But some artisanal mines are run by armed groups involved in massacres of civilians, mass rapes, looting and other crimes, according to United Nations experts and human rights groups, leading campaigners to urge companies to shun these "conflict minerals".

A request for comment has been sent to Apple ( AAPL ).

In December, the iPhone maker said that it strongly disputed the claims and had instructed its suppliers earlier in 2024 not to use the minerals in question sourced from Congo or Rwanda.

Congo's lawyers said at the time that they welcomed Apple's ( AAPL ) statement with "satisfaction and caution."

(Writing by Portia Crowe; Editing by Mark Potter)