Obama says: Nuclear terrorism is World's major threat

US President Barack Obama on today underlined greater urgency in safeguarding the world's atomic stockpiles, warning that nuclear terrorism remained one of the world's major threats.

Speaking hours before the commencement of a nuclear security summit in South Korea, the US leader noted that key progress had been made to make it harder for terrorists to acquire material required for building atomic weapons.

He added: "But we're under no illusions. We know that nuclear material -- enough for many weapons -- is still being stored without adequate protection.”

"We know that terrorists and criminal gangs are still trying to get their hands on it, as well as the radioactive material for a dirty bomb... the danger of nuclear terrorism remains one of the greatest threats to global security."

Obama urged the leaders or top officials from 53 nations who had gathered in the South Korean capital, Seoul, for the March 26-27 summit to take concrete steps to secure nuclear materials.

"This is the serious and sustained global effort we need. This is an example of more nations bearing the responsibility and the costs of meeting global challenges," he said.