Police in Namibia are investigating the death of four children who were playing in an empty old freezer in the north-eastern Zambezi Region.

Aged between three and six, the children were found inside the unused deep freezer in the densely populated area of the town of Katima Mulilo on Monday afternoon.

The police believe the children were accidentally trapped while playing and suffocated inside but investigations are under way.

Of the four children, two suffocated to death in the fridge while two others died in the hospital while receiving treatment, the public broadcaster reported.

“When I came in, I saw paramedics attending to my daughter and another girl. They rushed them to the hospital, while the other two were loaded in police mortuary vehicles,” Aranges Shoro, one of the fathers, told privately-owned The Namibian newspaper.

"There was a hook on the freezer that could only be opened from the outside," Zambezi regional police commander Andreas Shilelo is quoted by the AFP news agency as saying.

"They were stuck for about an hour and a half and suffocated."

The two who were rushed to the nearby Katima Mulilo State Hospital were declared dead upon arrival, the public broadcaster NBC's news website reported.

It is not clear why the non-functional freezer was left outside a house of one of the affected families.