Washington: The United States has expressed concern over nuclear weapons of India and Pakistan, but parried queries on Pakistan's nuclear co-operation with "rogue" states like North Korea and Iran and fears raised on such weapons falling into the hands of terrorist organisations due to such co-operation.

Senior State Department official, undersecretary of state John R Bolton, while recently testifying before the House International Relations Committee in Washington said nuclear weapons of India and Pakistan is "of enormous concern".

"…The subject of Pakistan's nuclear weapons and India's nuclear weapons…is of enormous concern," he said observing that countries that possessed or aspired to possess weapons of mass destruction were of "immediate concern" to US and friends and allies.

He, however, skirted questions about Pakistan's import of missiles from North Korea and payment in nuclear technology and equipment for North Korea's efforts to produce weapons-grade uranium by centrifuge and its reported aid to Iran.

When pressed by Congressman Joseph Crowley, co-chairman of the India Caucus, Bolton said Pakistan had denied the report on nuclear know-how and equipment and on the issue of purchase of missiles from North Korea.

When Crowley specifically asked Bolton if he was suggesting that India is also engaged in delivering nuclear technology to terrorist states or to terrorist organisations, the official said, "No, Sir. I was referring to Indian and Pakistani nuclear capabilities."

PTI