Immigration authorities in Zimbabwe arrested 3,967 people over the Christmas holidays for trying to cross the border illegally.
Reports said those detained included 200 children, mainly from Harare and Bulawayo, who were on their way to be with their families in Johannesburg and Cape Town.
The state-run Herald says the majority were arrested for breaching the Immigration Act for having no passports, or for failing to get them stamped. Ten were fined for people smuggling.
Tens of thousands of Zimbabweans live and work in South Africa, and the smuggling of children across the border to join families spikes during the Christmas season.