Chishimba Kambwili was arrested on Wednesday for diffusing a video in which he said "some dogs from Chawama do not get tired of travelling".
Chawama is a slum in Zambia's capital Lusaka where Lungu lived and served as member of parliament before taking over the presidency in 2015.
Kambwili's trial has been scheduled to begin on September 30. If convicted, he could face up to three years in prison.
A leader of Zambia's opposition denied defamation charges in court on Friday after being arrested for a video in which he allegedly refers to President Edgar Lungu as a dog.
Chishimba Kambwili, head of the National Democratic Congress (NDC), was arrested on Wednesday for diffusing a video in which he said "some dogs from Chawama do not get tired of travelling".
Chawama is a slum in Zambia's capital Lusaka where Lungu lived and served as member of parliament before taking over the presidency in 2015.
Lungu also made various trips abroad this month, prompting police to infer that Kambwili—a fierce critic of Lungu's regime—was referring to the president.
"I understand the charge. I plead not guilty," Kambwili told magistrate Lameck Mwale during a court appearance in Lusaka. He was granted release on bail.
Prosecutors maintained that he intended to "ridicule" Lungu and "bring the name of the president into hatred".
Kambwili's trial has been scheduled to begin on September 30. If convicted, he could face up to three years in prison.
Various opposition politicians in Zambia have accused Lungu of cracking down on dissent—a charge the government denies.
Kambwili served as a lawmaker for the ruling Patriotic Front (PF) until he was fired in 2016 and became a vocal critic of the regime. He was arrested last year for inciting public violence, but the case was dropped.
His NDC party was banned from holding public meetings in 2018 and effectively shut down earlier this week.
Lungu travelled to India for a three-day state visit this month, and is in Japan this week to take part in development talks with other African leaders.
