Witnesses say Congolese police in Lubumbashi fired tear gas and threw rocks at demonstrators supporting an opposition leader during his court hearing.

Moise Katumbi was summoned to court on allegations he hired mercenaries. His lawyer, Georges Kapiamba, said Friday's hearing was suspended at Katumbi's request, saying he was not feeling well because of tear gas.

Paul Koboba said police and youths threw rocks at each other. Katumbi's wife, Carine, said on Twitter one person was injured. Police did not immediately respond to requests for confirmation.

Katumbi resigned as a governor from Congo's ruling party last year. Last week he announced his intent to run in November elections as an opposition candidate. The opposition has alleged President Joseph Kabila may delay elections to hold onto power.