A senior UN food agency official called Thursday for urgent assistance for North Korea, stressing that Pyongyang has given the agency new monitoring powers to ensure aid is not diverted from the needy.

The plea came as the United States considers sending a team to the communist state to assess its needs.

Claudia von Roehl, the World Food Programme (WFP) director in Pyongyang, urged South Korean officials and lawmakers to help their impoverished neighbour, which she said was left "highly vulnerable to a food crisis".

"It is really upon you to show your responsibility for the future... and to decide to help, directly or indirectly, your brothers in need," she told a parliamentary forum.

Roehl said more than six million people including children urgently need aid after unseasonably cold weather and dwindling national wealth left the North unable to produce or import enough food for its 24 million people.

The figure is based on a report by the WFP and the UN's Food and Agriculture Organisation published in March.

Some Seoul officials have questioned the dire prediction, saying the recent harvest was relatively good and the communist state may be seeking to stockpile food for a major political anniversary in 2012.

The North traditionally gives its people extra rations to mark major dates.

The Seoul government halted its own major annual rice and fertiliser shipments in 2008 as relations worsened.

Donations to UN programmes have dwindled due to irritation at missile and nuclear programmes and questions about whether food is diverted to the army.

Roehl pledged to improve monitoring by getting more access to distribution venues and even private markets under an agreement signed with Pyongyang last month.

"We are... granted, for the first time ever, access to markets in both urban and rural areas... we are checking market prices of food being traded," she said.

"We will increase the presence of international staff up to 60... and more than half of those involve monitoring activities."

Roehl added that aid officials must give only 24 hours' notice to authorities before visits to private homes, markets or other venues, compared to a week in the past.

The United States in 2008 pledged 500,000 tonnes of rice. But shipments stopped the following year amid questions over distribution transparency and the North told aid officials to leave.

The State Department confirmed Wednesday it is considering sending an assessment team led by Robert King, the special envoy on North Korean human rights.

Spokesman Mark Toner said any decision on food aid would not be swayed by political considerations. But he attributed the North's shortages largely to "bad policies and the misallocation and mismanagement of resources" by its regime.