World leaders at a summit on nuclear security in the United States have heard dire warnings of the danger of nuclear material falling into the wrong hands.
Leaders or representatives of 48 nations have gathered for a summit in the United States called by President Barack Obama to look at measures to keep nuclear weapons from terrorists.
Officials said more should be done to prevent theft or smuggling, while the head of the International Atomic Energy Agency, Ikia Amano, said that nuclear powers needed to do more to protect nuclear materials.
The two-day summit is taking place without representatives of Iran and North Korea, neither of whom were invited by the US because of the disputes over their nuclear programmes, the BBC reports.
Israeli Prime Minister Benjamin Netanyahu dropped plans to attend the summit, reportedly because of concern that Muslim states planned to press for Israel to open its own nuclear facilities to international inspection.
Meanwhile, France's leader stressed his country could not give up its own nuclear weapons.
China set to help craft Iran sanctions, says US
China and the US have agreed to instruct their officials to work on the formulation of new sanctions against Iran over its nuclear programme, a US official says.
In a meeting ahead of the summit, Mr Obama stressed to Chinese President Hu Jintao the need to act urgently against Iran's nuclear programme. The official said Mr Hu agreed Beijing would help craft a UN resolution.
Iran has dismissed the meeting and said it would not be swayed by any decisions made in Washington.
President Mahmoud Ahmadinejad has sent a letter to the UN urging an investigation into the aims of western military actions in Afghanistan and Iraq.
Ukraine to get rid of highly-enriched uranium
Ukraine has agreed to eliminate its stockpile of weapons-grade nuclear material by 2012, the United States has announced.
White House spokesman Robert Gibbs said Ukraine intended to remove a "substantial part of its stocks" of highly enriched uranium this year and would convert its civil nuclear research facilities to operate with low enriched uranium fuel.
The move by Ukraine is designed to make it harder for terrorists to get hold of material that could be used in an atomic bomb.
The gesture from the site of the 1986 Chernobyl nuclear power plant explosion gave early impetus to the two-day summit.
New Zealand Prime Minister John Key, who is attending the summit, praised the US efforts at the meeting to increase nuclear security.
"New Zealand brings a long long history of showing leadership in this area, arguing that the world should be free of nuclear weapons," he said ahead of the meeting.
"Sure, we're a small country but we're not immune from risks like the rest of the world and we want to live in an environment where we're free of those nuclear weapons."