International lawyers representing the government of the Democratic Republic of Congo said on Wednesday new evidence gathered from whistleblowers indicates that Apple is sourcing minerals from conflict areas in the east of the country.

In a statement, the lawyers urged Apple to answer questions about its supply chain in the country, and said they were evaluating legal options. Apple did not immediately respond to a Reuters request for comment.

Congo has been ravaged by violence since the 1990s, particularly in the restive east, where a myriad of armed groups, some of them backed by neighbouring Rwanda, fight over national identity, ethnicity, and resources.

Congo's lawyers notified Apple CEO Tim Cook on April 22 of a series of concerns about its supply chain, and also wrote to Apple subsidiaries in France, demanding answers within three weeks. The Amsterdam & Partners law firm has been investigating allegations that minerals mined in Congo by several companies and armed groups are being smuggled out through Rwanda, Uganda and Burundi.

The firm said in a statement on Wednesday that, four weeks later, "the tech giant has remained silent and neither answered nor even acknowledged receipt of the questions."

One of the lawyers, Robert Amsterdam, said the firm has since received new evidence from whistleblowers.

"It is more urgent than ever that Apple provide real answers to the very serious questions we have raised," he said in the statement.

Apple has said in the past that it does not directly buy, procure or source primary minerals, and it has been auditing its suppliers for several years and publishing its findings.

In a report last year, it said that 100% of identified smelters and refiners in the supply chain for all applicable Apple products manufactured in 2023 had participated in an independent third-party conflict minerals audit for tin, tantalum, and tungsten, known as 3T minerals, and gold (3TG).

"We found no reasonable basis for concluding that any of the smelters or refiners of 3TG determined to be in our supply chain as of December 31, 2023 directly or indirectly financed or benefited armed groups in the DRC or an adjoining country," the Apple report said.

Another lawyer from Amsterdam & Partners, Peter Sahlas, told Reuters that people who worked on Apple's supply chain verification in Congo had come forward to say that their contracts were terminated after they flagged concerns that "blood minerals" were in Apple's supply chain.

"We are engaging with these individuals and evaluating their evidence and will have more to say once we have completed robust verifications," Sahlas said, without giving further details.

Since the letter issued by Congo lawyers in April, clashes have intensified in eastern Congo where Rwandan-backed M23 rebels have seized control of Rubaya, a key mining town for coltan used in smartphones and other appliances.