KINSHASA, Congo (AP) — A rebel group with alleged links to Rwanda this week seized Rubaya, a mining town in eastern Congo known for producing a key mineral used in smartphones, the group said Thursday in a statement.

In a statement shared with The Associated Press, a spokesperson for the M23 rebel group said the town was “liberated.”

The Congolese army declined to comment on the situation.

The decadeslong conflict in eastern Congo has produced one of the world’s worst humanitarian crises, with over 100 armed groups fighting for control of the mineral-rich area near the border with Rwanda. Many groups are accused of carrying out mass killings, rapes and other human rights violations. The violence has displaced about 7 million people, many beyond the reach of aid.

The town of Rubaya holds deposits of tantalum, which is extracted from coltan, a key component in the production of smartphones. It is among the minerals that was named earlier this month in a letter from Congo’s government questioning Apple about the tech company’s knowledge of “blood minerals” being smuggled in its supply chain.