A divided US Senate panel approved Chuck Hagel as the next US secretary of defense on Tuesday, a key step in a process that could see the controversial nominee confirmed as early as this week.

The Senate Armed Services Committee split along party lines by 14 votes to 11, to narrowly approve the former Republican senator whose positions on Iran, Israel and the Iraq war sparked concerns by fellow conservatives.

If approved by the full Senate, Hagel would replace outgoing Pentagon chief Leon Panetta at a time of rising tension in Middle East hotspots, in the budget battle at home and after this week's rogue nuclear test by North Korea.

The tense, two-hour hearing saw lawmakers verbally sparring over Hagel's qualifications, his occasionally evasive responses to senators' questions and even his patriotism.

Some of the harshest criticism came from Senator Lindsey Graham, who said Hagel was well outside both the left or right lanes of American foreign policy.

"When it comes to some of the Iranian (and) Israeli issues, there's the Chuck Hagel lane. He's in a league of his own, guys," Graham said.

With Hagel, it has been "a series of things, a series of votes, an edge about him that makes many of us very unnerved about his selection at a time when the world is on fire."

Before the vote, Graham told reporters he would seek to block Hagel's confirmation, but Democratic Majority Leader Harry Reid brushed aside the threat, saying he expected to bring a vote to the Senate floor "this week."

Should Reid be forced to overcome a procedural block, a vote to proceed would require 60 votes rather than a simple majority of the 100 seat body.

Democrats have a 55 to 45 edge in the chamber. All the Democrats are expected to back Hagel and at least two Republicans -- Senators Thad Cochran and Mike Johanns -- have said they would.

But the committee debate showed intense partisan differences, with Republicans seeking more time to receive information about payments Hagel received for several of his speeches in recent years.

"This vote is being rushed," Senator David Vitter told the committee.

Newly elected Senator Ted Cruz of Texas angered Democrats when he demanded that Hagel release more personal financial information, suggesting Hagel could have been influenced by foreign countries or "extreme radical groups."

That prompted a fierce retort by Democratic Senator Bill Nelson, who said he believed "Senator Cruz has gone over the line.

"He basically has impugned the patriotism of the nominee... about him in essence being cozy with Iran.

The sparring eventually led John McCain, a Republican and Hagel's fellow Vietnam War veteran who fell out with him in part over Hagel's opposition to the US troop surge during the Iraq war, to step in.

"Senator Hagel is an honorable man. No one should impugn his character or integrity," McCain said.

Levin told the committee that despite Republican efforts to portray Hagel as "outside the mainstream," he has received broad support from former secretaries of defense and other senior statesmen.

"If there is a risk here it is that the defeat of this nomination would leave the Department of Defense leaderless at a time when we face immense budgetary challenges and our military is engaged in combat operations overseas," Levin warned.

Hagel endured withering cross-examination in lengthy testimony on January 31, when Republicans pressed him about his past statements and votes on Israel and Iran and its nuclear drive.

When Vitter repeated a proposal to delay the Hagel vote, Levin waved him off. "This could go on forever," he snapped. "We need a secretary of defense."