Pakistan's military knows there were would "catastrophic consequences, primarily for Pakistan," if any of its nuclear bombs fell into the wrong hands, the top US intelligence official said Wednesday.

Director of National Intelligence Dennis Blair's comments came one day after he told the Senate Intelligence Committee that "vulnerabilities exist" in Pakistan's nuclear safeguards.

"The Pakistan army takes very seriously the security of its weapons, and they know the catastrophic consequences -- primarily for Pakistan -- if they were to get loose," Blair told the House Intelligence Committee.

"From what we see of the measures that they take, they are keeping them safe," Blair told lawmakers concerned about the stability of Pakistan and the fate of its atomic arsenal as it grapples with Islamist extremists.

On Tuesday, Blair told senators in an annual assessment of global threats to US interests, "We have confidence in Pakistan's ability to safeguard its nuclear weapons, though vulnerabilities exist."

He did not elaborate.