KINSHASA, Congo (AP) — The political party of Etienne Tshisekedi says the Congolese opposition icon has died. He was 84.

Tshisekedi had sought medical treatment in Belgium late last month, and has long battled rumors of ill health. He had returned to Congo in late July after several years abroad.

The Union for Democracy and Social Progress said late Wednesday that its leader had died at Sainte Elisabeth Hospital in Brussels. The cause of death was not given.

His death comes at a politically fragile moment for the vast Central African nation, where the opposition protested for months to get President Joseph Kabila to agree to step down.

The parties signed a deal, but it has yet to be implemented. The stalemate already has worried observers.