Zambian police have arrested an opposition leader for allegedly training a militia to carry out violent acts ahead of general elections on Aug. 11.

Geoffrey Bwalya Mwamba, vice president of the opposition United Party for National Development, was released on Thursday. A day earlier, prosecutors filed charges against him and police fired tear gas to disperse his supporters.

Police say they arrested 21 youths and confiscated a pistol and other weapons at Mwamba's property in the Zambian capital, Lusaka.

Mwamba, who must return to court on March 10, denies the accusations and describes the legal action against him as "part of the continued struggle" for better living conditions for Zambians.