Police in Zambia have withdrawn permission for an opposition protest at alleged election fraud after riots, in which 38 people were arrested.
Shops were looted, cars stoned and a police station reportedly attacked.
"The current situation in the country is not suitable for such events," said Daniel Kasonde, a police commander in the area where the trouble broke out.
The opposition Patriotic Front (PF) has reportedly lodged an official challenge to the results of last month's poll.
PF leader Michael Sata says he was robbed of victory.
The official results gave ruling party candidate Rupiah Banda a narrow victory and he was immediately sworn in.
African regional election observers declared the poll free and fair.
Thursday's violence in the opposition stronghold of Kitwe came after the release of a priest arrested during a live radio show over charges of inciting possible hostility by alleging the elections were fraudulent.
Police detained Father Frank Bwalya while he was on air for the Roman Catholic church-owned Radio Icengelo.
The BBC's Boyd Chibale in Kitwe says earlier in the day hundreds of people supporting Father Bwalye - an influential figure in the town - had brought Kitwe to a standstill and many shops were closed for fear of riots.
Taxis and buses were tooting their horns and protesters in the crowd chanted: "We want change".