BAGHDAD – The U.S. military on Sunday announced the arrest of a suspect in the killing of a sheik who spearheaded the U.S.-backed Sunni revolt against al-Qaida in Iraq, even as the terror network launched a campaign of violence during the Islamic holy month of Ramadan.

Dozens of suspected Sunni insurgents raided Shiite villages north of Baghdad, killing at least 15 people and setting homes ablaze, police said. A bicycle bomb exploded at a cafe serving tea and food during the Ramadan fast in northern Iraq.

The surge of bloodshed – with 54 people killed or found dead nationwide – occurred a day after al-Qaida announced a new campaign aimed at countering U.S. and Iraqi claims the terror movement is reeling following the U.S.-led offensives around the Iraqi capital.

But the U.S. military insisted it had the group on the run and said a man believed responsible for the assassination of a U.S.-allied Sunni tribal leader in Anbar province had been arrested north of Baghdad.

Abdul-Sattar Abu Risha, 37, was the leader of Anbar Awakening – an alliance of clans backing the Iraqi government and U.S. forces against al-Qaida in Iraq that was touted as one of the success stories of the war. He and three companions were killed in a bombing Thursday outside his heavily guarded compound in the provincial capital of Ramadi, days after he had met with President Bush.

The U.S. military said an al-Qaida-linked militant connected to his death and a plot to kill other tribal leaders – Fallah Khalifa Hiyas Fayyas al-Jumayli, an Iraqi also known as Abu Khamis – was seized Saturday during a raid west of Balad, and the search continued for other suspects.

Brig. Gen. Joe Anderson, chief of staff to the No. 2 commander in Iraq, said al-Qaida fighters were “off-balance” and had “clearly been neutralized” in Baghdad.

“They are very fractured. It’s very localized and the ability for them to conduct large-scale, sensational attacks has been greatly decreased,” Anderson said at a news conference.

In the raids on the Shiite villages of Jichan and Ghizlayat, the fighters arrived from several different directions and residents fought back until Iraqi security forces arrived and forced the attackers to flee to nearby farms.

Iraqi police and army officials said 15 people were killed and 10 wounded, including two children, in the clashes some 60 miles north of Baghdad.

Mohammed Azzawi Ali al-Timimi, 30, said he was out buying supplies for his store when the attacks occurred. He returned home to devastation.

“When I came back to my Jichan village I was shocked to find that my father had been killed, along with two of my brothers and my 7-year-old nephew,” he said. “Four other houses of my relatives were attacked as well and more than eight cars were burned out.”

Farther north, a booby-trapped bicycle exploded in the religiously mixed town of Tuz Khormato, killing at least five people and wounding 19.

Witnesses said a boy left the bike near the outdoor cafe, which was in a popular market and was one of the few open during daylight hours despite Ramadan. Tradition requires the faithful to abstain from eating and drinking from sunrise to sunset during the monthlong observance.

Two of the slain victims were in the cafe, while three were in the market, police chief Capt. Abbas Mohammed said.

No one claimed responsibility, but the attack bore the hallmark of Sunni insurgents led by al-Qaida and underscored militants’ ability to find new ways to thwart stringent security measures.

In Baghdad, Iraqi police said security contractors opened fire in a predominantly Sunni neighborhood of western Baghdad on Sunday, killing at least nine civilians.