Hours after a US study warned of a "very real possibility" that deadly warheads could be stolen by extremists singling out Pakistan as a likely source, Prime Minister Yusuf Raza Gilani on Tuesday said his country's "nuclear weapons are safe and well-guarded".
Trying to allay misgivings, Gilani said "Islamabad has taken effective steps for nuclear safety, security and nonproliferation through extensive legislative, regulatory and administrative framework".
Harvard University released a study warning that four terror groups -- al-Qaeda, Lashkar-e-Taiba, Chechnya-based separatists and Japanese extremist group Aum Shinnko, were hunting for warheads.
The study, 'Securing the Bomb' conducted by the Belfer Centre of the University, and released today said that al-Qaeda was in the hunt for nuclear weapons for the last 10 years and had twice attempted to buy fissile material in black market.
It said Pakistan faces a greater threat from Islamic extremists seeking nuclear weapons than any other country on Earth. The new report from Harvard nonproliferation experts found that Pakistan's stockpile is the world's least secure from theft or attack.
The study compiled by experts in the University was released as US President Barack Obama's Nuclear Summit convened in Washington and immediately raised the ire of Pakistan's Prime Minister.
On Sunday, the US President had also warned that al-Qaeda continues to seek materials to build an atom bomb and is banking on the current summit to help him reach his goal of ensuring that all nuclear materials worldwide are secured within four years.
Pakistan's leaders insist their stockpiles are safe and contend their country follows the regulations set by the International Atomic Energy Agency.
"We are confident our system is second to none," said Foreign Minister Shah Mahmood Qureshi, who was also present at his Prime Minister's interaction with the media.
"We have world class measures in place," he claimed.
But the study, commissioned by the Nuclear Threat Initiative found that Pakistan faces formidable risks in safeguarding its nuclear warheads.
While acknowledging substantial security improvements in the last few years, the study notes that the danger persists from "nuclear insiders with extremist sympathies, al-Qaeda or Taliban outsider attacks, and a weak state."