The US Senate on Thursday approved a vast military spending bill that tied strings to military aid to Pakistan and aimed to stem the spread of shoulder-fired anti-aircraft missiles from Libya.

The $662 billion annual Defense Authorization legislation also included a murky compromise on the issue of whether the US government may hold suspected terrorists, including American citizens, indefinitely without trial.

The bill, which sailed to passage by a lopsided 93-7 margin, included tough new sanctions aimed at cutting off Iran's central bank from the global financial system in a bid to force Tehran to halt its alleged nuclear program.

Lawmakers feuded for much of the week on the legislation's affirmation of past judicial opinions that US citizens who sign on with Al-Qaeda or affiliated groups may be held indefinitely without trial.

Senators repeatedly rejected efforts to exempt Americans from that fate, but ultimately voted 99-1 to embrace a face-saving compromise that left the volatile issue to the US Supreme Court.

"The Supreme Court will ultimately decide who can, and cannot, be detained indefinitely without trial," said number-two Democratic Senator Dick Durbin. "The United States Senate will not."

Senate Armed Services Committee Chairman Carl Levin insisted that the high court had already ruled "there is no bar to this nation holding one of its own citizens as an enemy combatant" but acknowledged deep divisions on that issue.

"If that law is there allowing it, it remains. If, as some argue, the law does not allow that, then it continues that way," said Levin, a Democrat, highlighting the compromise's deliberate vagueness.

The White House, which previously had issued a vague threat to veto the bill over the detainee provisions, had no immediate comment, but Human Rights Watch and Amnesty International urged him to stand firm.

The legislation did exempt US citizens from a requirement that Al-Qaeda fighters who plot or carry out attacks on US targets be held in military, not civilian, custody, subject to a presidential national security waiver.

Critics expressed worries that tough new standards for transferring detainees to other countries -- notably a requirement that top US officials formally declare them no longer a threat -- could hamper the American exit from Afghanistan, where US forces hold thousands of prisoners.

The legislation included a provision by Democratic Senator Bob Casey aimed at blocking counterinsurgency aid to Pakistan until Islamabad takes aggressive steps to curb the use of roadside bombs blamed for the deaths of US soldiers in neighboring Afghanistan.

It also included an amendment from Republican Senator Susan Collins that calls for US-Libya cooperation to secure slain dictator Moamer Kadhafi's stockpile of 20,000 portable anti-aircraft missiles.

US officials fear terrorists could get their hands on such weapons in the chaotic aftermath of Kadhafi's ouster.

And it included Republican Senator John McCain's amendment calling for closer military ties with Georgia, including the sale of weapons he said would help the country, which fought a brief war with Russia in 2008, defend itself.

The bill also contained Democratic Senator Jeff Merkley's call for an assessment of the feasibility of accelerating the US troop withdrawal from Afghanistan, where combat operations are due to end come 2014.

And it included Republican Senator Roger Wicker's amendment stating that US military chaplains are not required to perform gay marriage.

Senate approval touched off negotiations with the House of Representatives to resolve differences between both chambers' versions and send a compromise to President Barack Obama.