The DA leader travelled to Zambia with an intention of attending the treason trial of Hakainde Hichilema, the detained President of Zambia’s largest opposition party – the United Party for National Development (UPND).
Hichilema is alleged to have attempted to block Zambian President Edgar Lungu’s motorcade, which was travelling on the same road.
The treason trial will be held on Friday at the Magistrate Court Complex, Hibiscus Road, Lusaka, Zambia.
Speaking on Talk Radio 702 Maimane, who is scheduled to give more details at a press conference he will hold at the Zambian embassy in Pretoria later on Friday, said he and his colleagues were manhandled for about an hour by Zambian authorities.
He warned that democracy in Zambia was "falling apart".
Maimane returned to South Africa on Thursday after being forcefully prevented from entering the Republic of Zambia.
"The leader of the official opposition is a constitutional office bearer of the the Republic of South Africa, and the actions of the Republic of Zambia tonight deserve serious attention by the South African government," said the DA after the unprecedented Zambian move.