A top US diplomat said Wednesday ensuring food aid to North Korea reached the most vulnerable was "complicated", ahead of talks with Pyongyang officials in Beijing to finalise plans for assistance.

North Korea said last week it would suspend its nuclear tests and uranium enrichment programme in return for US food aid, following talks with the United States less than three months after the death of leader Kim Jong-Il.

Robert King, the US envoy on human rights in North Korea, told reporters he would meet with a counterpart from Pyongyang to discuss how the 240,000 metric tonnes of food aid will be delivered to the most needy in the communist state.

"The food nutrition assistance programme we are here to talk about is a complicated programme and we need to work out the details in terms of how we are going to carry that programme out," King said.

King said the food aid would target "a million or more" people in the impoverished country, mostly children, pregnant women and the elderly which officials have said would decrease the chances of diversion to the military.

"We need to make sure that we have the right procedures in place to make sure that the assistance reaches those we are trying to help," he said.

The surprise agreement between Pyongyang and Washington was reached in Beijing last month, which marked the first contact between the two sides since Kim Jong-Un took power in late December following the death of his father.

The discussions were aimed at persuading the North to return to the six-nation denuclearisation talks after it angrily abandoned them in April 2009 and staged its second atomic weapons test a month later.

The two Koreas, Japan, China, Russia and the United States have been talking for months about ways to revive the discussions.

Analysts have expressed cautious hope that the US-North Korea deal might signal a more conciliatory posture from Pyongyang, which has built up a costly nuclear programme despite suffering from dire food shortages and poverty.

North Korea in November 2010 publicly disclosed the uranium enrichment programme, which could give it a second way to make atomic weapons. Its longstanding plutonium programme is believed to have produced enough material for six to eight weapons.