The Washington nuclear security summit missed an opportunity to adequately address the dangers posed by so-called dirty bombs which, while not as deadly as a homemade atomic weapon, are easier to obtain, an expert in nuclear non-proliferation law and policy told Xinhua in a telephone interview on Wednesday.

"In some senses, the greater danger is the use of radioactive materials that are used to create the dirty bomb, or the radiation dispersal device," said Carlton Stoiber, the chairman of the Working Group on Nuclear Security of the International Nuclear Law Association headquartered in Brussels, Belgium.

"If the terrorists were to use a radiation dispersal device it would be far less serious than a nuclear explosive, but it's so much more likely that I think the security summit should have given it more attention," said Soiber, who is now in Washington, D.C..

Radioactive material used in medicine, agriculture and other industries can be found in thousands of locations around the world, and are often poorly controlled and safeguarded.

But by placing a higher priority on highly enriched uranium ( HEU) and plutonium, which are used for nuclear explosive devices, world leaders at the summit missed the chance to raise awareness on securing materials found in dirty bombs, said Stoiber.

The Nuclear Security Summit held in Washington, on April 12-13, was billed as the largest meeting of world leaders on U.S. soil since the United Nations was established in San Francisco in 1945.

Stoiber, who has over 30 years of experience negotiating numerous bilateral and multilateral legal instruments in the nuclear field, said he was pleased to finally see so many heads of state engaged in a discussion on securing fissile material. In the past, such dialogue has often been relegated to second and third- level officials, he said.

In a non-binding communique issued at the closing of the summit on Tuesday, the 47 participating states reaffirmed "the essential role of the International Atomic Energy Agency in the international nuclear security framework" and pledged to "work to ensure that it continues to have the appropriate structure, resources and expertise needed to carry out its mandated nuclear security activities."

The leaders also agreed to hold another nuclear security summit in the Republic of Korea in 2012, a meeting Stoiber hopes will tackle the question of unsecured radioactive materials.