South African border officials said 443 children under the age of eight were found travelling from Zimbabwe without parents or legal guardians.

The children were being "trafficked" into South Africa, the officials said.

Police stopped and searched the 42 buses entering through the Zimbabwean side of the Beitbridge border post on Saturday evening, and they were then sent back to Zimbabwe.

"We denied them entry and activated the Zimbabwean officials to process them back into Zimbabwe," said Mike Masiapato, commissioner of South Africa's Border Management Agency.

However, an organisation representing foreign nationals living in South Africa has suggested another possible explanation for their entry into Zimbabwe.

The Africa Diaspora Forum said it believed the children were being sent to visit their parents who are working in South Africa.

Ngqabutho Mabhena, chairman of the organisation, said it was common that children were sent over the border without proper documentation, particularly near the end of the year.

Mr Mabhena said: "We always tell Zimbabwean parents living in South Africa that, if they arrange for their children to come to South Africa, they must... arrange all necessary documentation.

"It is irresponsible for parents to let children travel without passports and to travel with strangers. We have addressed this with parents."

Read more from Sky News:
Woman dies after shark attack while swimming with daughter
Florence Pugh struck in the face by thrown object
Shoppers warned about smelly cheese described as 'just too much' for some

More than a million Zimbabweans live in South Africa, Africa's most advanced economy - many of them illegally.

Many moved over the last 15 years to escape economic turmoil in Zimbabwe.

South Africa launched a new border force in October to clamp down on illegal migration.