Organizers of the protests attracting minority Iraqi Sunnis insist they have no links to terrorist groups. Yet Iraqi and U.S. officials have expressed concern that violent extremists could benefit from the demonstrators' feelings of alienation and hostility toward the Shiite-led Iraqi government.

And tensions are rising.

At least five protesters were killed and more than 20 were wounded on Friday when soldiers opened fire at stone-hurling demonstrators near Fallujah, a former al-Qaida stronghold where tens of thousands took to the streets. Some in the crowd waved black banners emblazoned with the Muslim confession of faith.

They were the first deaths at opposition rallies that have been raging around the country for more than a month. Two soldiers were later killed in an apparent retaliatory attack.

Protesters also have staged demonstrations in other areas with large concentrations of Sunni Arabs, who feel discriminated against by the government. Their list of demands includes the release of detainees and an end to policies they believe unfairly target their sect.

For now, the American Embassy has no indication that al-Qaida is gaining support from the demonstrations. But the fear remains, particularly as the security situation deteriorates in neighboring Syria.

An embassy official said the U.S. had expressed concern that the protesters' peaceful expression of their viewpoints must not be usurped by extremists trying to provoke violence. The official spoke on condition of anonymity because he was not authorized to speak publicly about the matter.

Sectarian violence that once pushed Iraq to the brink of civil war has ebbed significantly, though violent attacks aimed mainly at Iraq's Shiite majority, security forces and civil servants still happen frequently.

Insurgents have managed to mount large, mass-casualty bombings of the type favored by al-Qaida on at least five days this month. In another attack, a suicide bomber killed a total of seven when he assassinated a prominent politician who played a leading role in the fight against al-Qaida.

The extremist group later claimed responsibility for the latter bombing and other unspecified attacks.

At least 170 people have been killed in insurgent violence since the start of the year, making January already the deadliest month since September.

Protest organizers and the politicians who support them are eager to distance themselves from extremist rhetoric.

Sunni lawmaker Ahmed al-Alawani recently urged Iraq President Nouri al-Maliki to meet demonstrators' demands so al-Qaida and other militant groups could not exploit their frustration.

That was a sentiment echoed by protest organizer and spokesman Saeed Humaim in Ramadi, a city in western Iraq that has been the focus of daily sit-ins and frequent mass rallies. He said protesters have no intention to take up arms, but will defend themselves if attacked by government security forces.

Still, many Iraqi Sunnis have little doubt that the protests strengthen militant groups.

"I don't think the al-Qaida people would miss an opportunity to move freely when the government and security forces are busy handling these spreading protests," said Ayad Salman, 42, who owns a shoe store in northern Baghdad. "The country is slipping toward a new round of civil war, or at least some groups are planning and pushing for this."

The rallies broke out just over a month ago in Iraq's western Sunni heartland of Anbar following the arrest of guards assigned to the Iraqi finance minister, a Sunni who hails from the province. The vast desert territory on Syria's doorstep was the birthplace of the Sunni insurgency that erupted after the 2003 U.S.-led invasion, and where Iraqi officials believe al-Qaida's Iraq arm is regrouping.

In an interview aired late Thursday, the Iraqi prime minister suggested that al-Qaida and members of Saddam Hussein's ousted regime have a hand in the demonstrations.

"I hope that these protests would not turn violent ... and drag the country to a sectarian war," he told al-Baghdadiya TV.

Al-Qaida's local affiliate this week posted a statement praising the protesters, saluting what it called "the true Muslims who revolted in defense of their honor and religion."

A senior Iraqi security official who specializes in terrorist activities said al-Qaida is making use of the resentment in predominantly Sunni provinces, where local residents who used to provide authorities tips about terrorist activities are growing much more reluctant to snitch.

He and another senior security official said al-Qaida fighters now have more freedom to move around. That is partly because state security forces' movements are being restricted in Sunni areas so they cannot be accused of unfairly targeting the Muslim sect, they said.

The second official said the demonstrations give extremists a good opportunity to try to mobilize Sunni opposition and portray themselves as the only groups who can safeguard the rights and interests of the Sunni minority.

The Iraqi officials insisted on anonymity because they were not authorized to discuss security operations with the media.

The local wing of al-Qaida, known as the Islamic State of Iraq, generally does not operate beyond Iraq's borders. But al-Qaida leader Ayman al-Zawahri last year urged Iraqi insurgents to support the Sunni-based uprising in neighboring Syria against President Bashar Assad, whose Alawite sect is a branch of Shiite Islam.

Iraqi officials believe Sunni fighters aligned with al-Qaida's Iraq franchise are moving back and forth across the Syrian border to help Sunni rebels overthrow Assad.

Rebel gains in Syria are giving Iraq's Sunni protesters and insurgents alike a sense that their fortunes may be shifting too.

"Sunnis seem ascendant in Syria. That is a major psychological boost to the Sunnis in Iraq," said Kamran Bokhari, an expert on Mideast issues for the global intelligence company Stratfor. "They're trying to capitalize on that."

Other militants are trying to tie their fight to the protests too.

Earlier this month, uniformed members of the Naqshabandi Army appeared in an online video urging Iraqis to continue their protests, sit-ins and acts of civil disobedience. It called on security forces to turn their weapons on the "traitors and foreign agents" — a likely reference to what many Sunnis see is Shiite powerhouse Iran's influence over the government.

The group, a network of former Iraqi military officers and jihadists, frequently claims responsibility for attacks on government security forces.

The highest ranking member of Saddam's regime still at large, Izzat Ibrahim al-Douri, has separately lent his support to the demonstrators. Al-Douri, who is suspected of having ties to the Naqshabandi Army, is thought to have played a key role in financing Sunni insurgents seeking to undermine Iraq's post-Saddam government.

Another small jihadist group, the 1920 Revolution Brigades, put out a statement of its own backing the protest movement.