Terrorists on the verge of acquiring N-weapons: US

US President Barack Obama has said terrorist organisations like Al Qaeda are aiming at laying their hands on nuclear weapons, which would be catastrophic for the world.

"The central focus of this nuclear summit is the fact that the single biggest threat to US security, both short term, medium term and long term, would be the possibility of a terrorist organisation obtaining a nuclear weapon," Obama told reporters in between his series of bilateral meetings with world leaders, including Prime Minister Manmohan Singh.

"So far today I've already met with Prime Minister Singh of India, as well as President of Kazakhstan, and now we are meeting with the President of South Africa," Obama said.

Later he met the Prime Minister of Pakistan, Yusuf Raza Gilani. All the meetings were held at the Blair House across the White House.

Nuclear terrorism, Obama said, is something that could change the security landscape of this country and around the world for years to come.

"If there was ever a detonation in New York City, or London, or Johannesburg, the ramifications economically, politically, and from a security perspective would be devastating," he asserted.

"We know that organisations like Al Qaeda are in the process of trying to secure a nuclear weapon -- a weapon of mass destruction that they have no compunction at using," he said.

"Unfortunately, we have a situation in which there is a lot of loose nuclear material around the world. And so the central focus for this summit is getting the international community on the path in which we are locking down that nuclear material in a very specific time frame with a specific work plan," Obama said.

"One of the things that I'm very pleased about is that countries have embraced this goal and they're coming to this summit, not just talking about general statements of support but rather very specific approaches to how we can solve this profound international problem," he said.

Praising South Africa for deciding not to go ahead with its nuclear weapons programme Obama said, "I wanted to especially single out South Africa because South Africa is singular in having had a nuclear weapon programme, had moved forward on it, and then decided this was not the right path; dismantled it; and has been a strong, effective leader in the international community around non-proliferation issues".