By Patrick Markey and Aseel Kami

BAGHDAD (Reuters) - Al Qaeda's Iraqi wing on Thursday urged Sunni protesters to take up arms against Shi'ite Prime Minister Nuri al-Maliki, adding fuel to growing sectarian unrest in the world's fastest-growing oil exporter.

Al Qaeda's local affiliate Islamic State of Iraq said "peace and patience" were useless for dealing with the Shi'ite-led government they see as oppressors of Iraq's Sunni minority.

"You have two options, not three: either kneel before the apostates, though that will be impossible, or to take up arms," Abu Mohammed al-Adnani, the group's spokesman said in an audio statement posted on a jihadist website.

Thousands of Sunni Muslims have rallied mostly in the western province of Anbar since December over frustrations they have been sidelined since the fall of Saddam Hussein in 2003.

Maliki says he will address legitimate demands, but warned against militants hijacking protests, heightening concern the OPEC nation risks worsening Shi'ite against Sunni confrontation.

Weakened by war with U.S. and Iraqi troops, Islamic State of Iraq last year vowed to retake ground lost to the government.

With Sunni Islamist militants flowing into neighbouring Syria to battle President Bashar al-Assad, security experts say al Qaeda is gaining funds, recruits and morale on both sides of the border, after years of losses.

Assad, whose ruling minority sect is a distant offshoot of Shi'ite Islam, is closely allied to Iran. The mostly Sunni rebel battle against his rule has started to threaten to upset Iraq's own fragile sectarian and ethnic balance.

GROWING DEMANDS

Sunni leaders say they want changes to an anti-terrorism law and to a law aimed at weeding out former members of Saddam's outlawed Baath party, which they believe have been used to unfairly target their community.

In a report released on Thursday, Human Rights Watch said Iraq's authorities used "draconian" measures against opposition leaders, detainees and demonstrators with security forces carrying out arbitrary arrests and abusive interrogations.

Seeking to defuse the crisis, the government has raised salaries for Sunni tribal militia who once fought al Qaeda, reviewed cases of prisoners and halted arrests made based on information from secret informers.

But Sunni ranks are split and hardliners and Sunni Islamists are calling for Maliki to step down. Some are pushing for an autonomous Sunni Muslim region inside Iraq.

Tensions exploded into clashes in Falluja last week when soldiers killed five people. Insurgents tied to al Qaeda have stepped up attacks trying to spark sectarian confrontation.

Al Qaeda claimed responsibility for a suicide bombing also in Falluja city earlier this month that killed a Sunni lawmaker.

Violence has eased since the 2006-2007 sectarian bloodbath, but al Qaeda and Sunni Islamists have carried out at least one big attack each month since the last U.S. troops left last year.

(Reporting by Patrick Markey; Editing by Jason Webb)