Chishimba Kambwili. Picture: Supplied by Zambian government.

Lusaka - Zambian opposition leader Chishimba Kambwili pleaded not guilty to charges of defamation against the country's president on Friday during an appearance at the Lusaka Magistrate's Court.

Kambwili, leader of the National Democratic Congress, was released on bail and a trial has been set for September 30.

Kambwili was arrested on Wednesday for allegedly defaming President Edgar Lungu. He is alleged to have made derogatory remarks about the president in a video clip that went viral on social media.

In the clip, he refers to "dogs from Chawama." The comment has been interpreted to refer to Lungu, who lived in Chawama and served as a member of parliament there.

Turning himself in for questioning on Wednesday, Kambwili told reporters he was not afraid of being arrested.

"It's just a question of people being scared of me. This is my ninth arrest in two years," he said.

Opposition politicians have repeatedly faced arrest and charges in the southern African country over the past few years, drawing accusations from human rights groups that the cases are politically motivated.

Another opposition leader, Hakainde Hichilema, was charged two years ago with high treason, but the case was later dropped.

dpa