Seven Afghan children were killed when an explosion occurred near a New Zealand firing range in Afghanistan, according to a report.

The blast happened in 2014 after a child discovered an explosive device at the range and carried it back to a nearby village, according to Stuff Circuit documentary Life + Limb.

Local woman Raina lost three children in the blast.

"We have lost them and nothing can bring them back," Raina told Stuff Circuit.

The New Zealand Defence Force says $10 million has been designated to clear its ranges in Afghanistan, which it left in 2013. Overseas militaries are in charge of clearing their firing ranges if they are in another country, according to the UN.

"You can't just leave unexploded ordnance behind in somebody else's country," head of UN Mine Action Service in Afghanistan Patrick Fruchet told Stuff Circuit.

Newshub has contacted the NZDF for a response to the documentary. A statement provided to Stuff Circuit said it "takes responsibility to ensure areas used by New Zealand forces are free of unexploded ordnance very seriously".