UNITED NATIONS (AFP) - International sanctions against North Korea have hit humanitarian funding for the isolated country, five UN agencies said on Monday in an appeal for help.

The agencies called for US$29.4 million (S$36.3 million) to pay for health and food supplies.

They indicated that "dire funding" provided for North Korea in recent months could threaten humanitarian operations in the country.

UN sanctions against North Korea have been stepped up after a long range rocket test last December and its third nuclear weapons test in February.

The UN Children's Fund (Unicef), World Food Programme (WFP), World Health Organisation (WHO) and the Food and Agriculture Organisation (FAO) said they were feeling fallout from North Korea's isolation.

"Even though the imposed sanctions clearly exclude humanitarian assistance, a negative impact on the levels of humanitarian funding has been experienced," the agencies said in a statement.

The agencies said they had received just over a quarter of the US$147 million they needed for operations in the North this year.

"As a result of the persisting deficit, agencies are unable to respond effectively to the humanitarian needs out of which the most critical and life-saving ones urgently require US$29.4 million," they added.

"The dire funding situation leaves the UN agencies and other humanitarian actors concerned about the continuation of their programmes" in North Korea.

The agencies said there had been "a slight improvement" in the humanitarian situation in the past year. But Unicef said it was running short of cash for basic vaccines and medicines for child killers such as pneumonia and diarrhea.

The UN estimates that about one-third of North Korean children under five are chronically malnourished. North Korea, which has a population of about 24 million, suffered famine-like conditions in the 1990s in which several hundred thousand people died, according to aid groups.