The United States plans to host a summit next March to discuss means of ensuring that nuclear materials cannot fall into the hands of terrorists, the White House said on Wednesday.

Nuclear security, particularly in relation to the North Korean and Iranian nuclear programs, is one of the main discussion points at the ongoing Group of Eight summit in Italy.

President Barack Obama "believes nuclear terrorism is the most immediate and extreme threat to global security," the AFP news agency quoted Mark Lippert, chief of staff of the U.S. National Security Council, as saying after the first day of the G8 summit.

The focus of the nuclear security talks, to which the leaders of up to 30 countries will be invited, will be on securing stockpiles of nuclear materials from theft, and improving global cooperation to counter the trafficking of fissile materials and nuclear technology.

"We think this is another important piece of the non-proliferation agenda that the president has put forward," he said.

The leaders of the eight countries taking part in the summit in the Italian town of L’Aquila drew up a joint statement on Wednesday urging North Korea to avoid further nuclear tests and ballistic missile launches.

The statement urges North Korea “to refrain from further violations of relevant Security Council resolutions and to engage in dialogue and cooperation.”

On Iran, French President Nicolas Sarkozy said the G8 would seek to resolve the dispute over the country’s nuclear program through dialogue, and that world leaders would review the situation at the G20 meeting to be held on September 24-25 in Pittsburgh.

"If there is no progress by then we will have to take decisions," he said.