With the White House's blessing, the US House passed legislation Wednesday to freeze some Pakistan aid, slap harsh new sanctions on Iran, and endorse indefinite imprisonment of suspected terrorists

US President Barack Obama, who had threatened to veto earlier versions of the yearly measure, will sign it when it reaches his desk despite lingering misgivings, spokesman Jay Carney said in a statement before the vote.

"However, if in the process of implementing this law we determine that it will negatively impact our counterterrorism professionals and undercut our commitment to the rule of law, we expect that the authors of these provisions will work quickly and tirelessly to correct these problems," said Carney.

The legislation, a compromise blend of rival House and Senate versions, requires that Al-Qaeda fighters who plot or carry out attacks on US targets be held in military, not civilian, custody, subject to a presidential waiver.

The bill exempts US citizens from that fate, but leaves it to the US Supreme Court or future presidents to decide whether US nationals who sign on with Al-Qaeda or affiliated groups may be held indefinitely without trial.

Obama had warned he could reject the original proposal over the military custody issue, as well as provisions he charged would short-circuit civilian trials for alleged terrorists.