A serious drought in North Korea requires urgent action to prevent the deaths of children already weakened by widespread malnutrition, the UN children's fund, UNICEF, warned Thursday.

"The situation is urgent. But if we act now -- by providing urgently needed expertise and prepositioning supplies -- we can save lives," said UNICEF East Asia Regional Director Daniel Toole.

"If we delay until we are certain of crop failures, it may well be too late to save the most vulnerable children," Toole said in a statement.

North Korea is currently suffering what its official media described last month as the "worst drought in 100 years" that has severely impacted main rice-growing areas.

According to the UN World Food Programme, early-harvest crops, mainly wheat and barley, have already been affected.

UNICEF said its personnel had recently met with local health officials in affected provinces who confirmed reports of significant increases in diarrhoea among children.

"Lack of rain reduces access to clean water and undermines effective hygiene, putting children's lives at risk," Toole said.

Concern about the impact of the drought is heightened by the existing poor nutritional status of many children in North Korea.

A 2012 study showed one-quarter of all North Korean children had symptoms of chronic malnutrition - a condition usually caused by a combination of unsafe water and poor sanitation, inadequate food intake, and inadequate access to health services.

Toole said responding to the current drought crisis was difficult given North Korea's isolation and the lack of funding for children-focused programmes in the country.

But UNICEF has released prepositioned emergency supplies to help those in the worst-affected provinces, including water purification tablets, water storage containers and health supplies for children with acute malnutrition.