The United States called off plans to send food aid to North Korea after the impoverished state's defiant rocket launch, as an aid group feared more than two million children would go hungry.

The United States had already suspended the plan to deliver 240,000 metric tons of assistance aimed at children and pregnant women as North Korea prepared what the regime called an unsuccessful bid to put a satellite in orbit.

President Barack Obama's administration, which had fine-tuned the aid package for months before announcing it February 29, said it was "impossible" to move forward after what US officials considered a flopped missile test.

"Their efforts to launch a missile clearly demonstrate that they could not be trusted to keep their commitments," deputy national security advisor Ben Rhodes said aboard Air Force One en route to Colombia for the Summit of the Americas.

"Therefore we are not going forward with an agreement to provide them with any assistance."

Under the February 29 deal aimed at easing longstanding tensions, the United States agreed to deliver aid under supervision in the authoritarian state and North Korea said it would freeze its nuclear and missile tests.

Asked if the food aid was off indefinitely, State Department spokesman Mark Toner said that the United States no longer "can frankly trust the North Koreans that this will end up in appropriate hands."

Hundreds of thousands of North Koreans are believed to have died in a famine in the 1990s. UN agencies estimated in November after a visit to the North that three million people would need food aid in 2012.

Mercy Corps, one of five US non-governmental groups that would have delivered the aid, said the assistance would have reached more than two million North Korean children and tens of thousands of pregnant women.

David Austin, the North Korea program director for Mercy Corps, said that the United States for generations had donated food to the needy regardless of political considerations.

"It is a shift to using food as a policy tool and it's one that we have a lot of concern about. We think it's become a distraction because it removes the focus from people who are in need and people whom we can save," he told AFP.

Austin visited North Korea in March and said he spoke to an administrator of an orphanage who told him that children were receiving 60 percent of normal daily rations and had not had any protein for two months.

Food delivery would come in bags emblazoned with the American flag and a message, "Free gift of the American people," he said.

"This is one of the only opportunities we have to create a connection between the people of North Korea and the people of the United States -- and a connection around saving the lives of children is a great way to engage," Austin said.

The European Union last year announced aid of 10 million euros ($13 million) in support for hungry North Koreans and the UN's World Food Program in the country. But Austin said parts of the country receive no outside help due to underfunding.

The Obama administration's food plan had been unpopular with many lawmakers of the rival Republican Party, who voiced concern that it would throw a lifeline to Kim Jong-Un's communist dynasty.

Representative Ed Royce, a Republican from California, had sought to bar US food aid, saying that the assistance would allow the regime to spend money on weapons.

After the launch, Royce called for a "new, comprehensive North Korea policy" that includes addressing human rights concerns and bringing outside information into the closed state.

North Korea is estimated by some experts to spend one-quarter of its budget on its military. In March 2009, the regime abruptly kicked out US aid groups who left behind some 20,000 metric tons of food from a previous deal.