Zambian President Hakainde Hichilema has warned ministers against dozing off during meetings, attributing their lack of attentiveness to "indulgence" and an absence of self-control.

"In cabinet somebody's sleeping at 10 hours - the question is where were they... if you can start conking there? To me, that is a crime, a serious crime," Hichilema said during a swearing-in ceremony for a new minister.

He did not spell out what exactly he meant by "indulgence", but local media have interpreted this as referring to excessive alcohol drinking and late-night partying.

The president warned that such behaviour risked exposing state secrets and delaying service delivery to the public.

Hichilema won a landslide victory in 2021 with ambitious plans to turn around the economy of Africa's second largest copper producer.

Since assuming office, he has sacked several senior officials, including ministers, over performance issues.

Speaking on Monday as he welcomed newly appointed Local Government Minister Gift Sialubalo, the president said he has now gone public with his concerns about cabinet members after saying it in private "over and over".

Without naming anyone, he said that some ministers "develop a knack" of revealing confidential state information on social media "especially during happy hours".

"I have advised cabinet that we must have a self-censure. When you're in public office you must have... self-control, not to over-indulge," the president added.

Citing the Bible, he warned such behaviour could lead to self-destruction.

"So, how do you participate in a meeting when you are sleeping? The message is very clear: you are not interested in cabinet deliberations on behalf of Zambians. So why are you sitting there?" he asked.

The president is expected to seek a second term in next year's general election. He could face stiff competition from his predecessor, Edgar Lungu, who has mounted a political come back but is currently barred from running.