Suicide bombers killed 20 members of Iraq's fledgling security forces near a US marine base west of Baghdad and at a checkpoint north of the capital on Saturday in a spate of guerrilla attacks across the country while the US troops said they caught a top aide to Iraq's most wanted man in the restive city of Fallujah.
The US military said it detained a senior member of Abu Musab al-Zarqawi's network and five other rebels during a pre-dawn raid in the Sunni Muslim bastion west of Baghdad which has been the focus of near-nightly air strikes in the hunt for the Jordanian-born militant.
The surge in violence underlined the scale of the task facing the US military and Iraq's interim government, which have sworn to crush the guerrillas before elections in January.
Hospital officials said 16 Iraqi police were killed and up to 40 people were wounded when a suicide bomber struck an Iraqi police post near the marine base.
Another suicide bomber blew up his vehicle near a checkpoint manned by Iraqi National Guards in the village of Ishaqi, close to the town of Samarra, north of Baghdad, killing four guards. A policeman was killed by a roadside bomb in Samarra.
There was no let up in violence elsewhere across the Sunni Arab heartland of central Iraq that the interim government and Washington blame on Saddam Hussein supporters and foreign militants.
Guerrillas killed two Turkish truckers and wounded two in an attack on a convoy near the northern city of Mosul, police said.
In central Baghdad guerrillas fired two mortar rounds, killing two civilians and wounding one, witnesses said. Six US soldiers were wounded when their armoured vehicle was hit by a bomb on a highway leading to Baghdad airport.
Saboteurs bombed two oil pipelines transporting crude from northern and eastern Iraq to Baghdad's Dora refinery. Neither pipeline carries oil for export.
The US military said it had captured a lieutenant of its top foe in Iraq, Abu Musab al-Zarqawi, and five other suspects in an overnight raid on what it said was a hideout of the Jordanian militant's network in the south of Falluja.
US forces also launched a new air strike on the rebel-held militant stronghold city, about 50km west of Baghdad, killing two people and wounding three.
US military did not name the man or give his nationality, but said he had once been viewed as a minor member of Zarqawi's militant Tawhid wal Jihad group.
"However, due to a surge in the number of Zarqawi associates who have been captured or killed by (US) strikes and other operations, the member had moved up to take a critical position as a Zarqawi senior leader," the military said in a statement.
SHRINKING HAVEN: It said Falluja was a shrinking haven for Zarqawi's group, widely blamed for some of Iraq's bloodiest violence. "Zarqawi followers are starting to move to outlying areas of Falluja in a continuing attempt to hide amidst the civilian population of Falluja due to precision strikes against Zarqawi hideouts and fighting positions," the military said.
Residents of Falluja deny knowledge of Zarqawi's militants and say frequent US air strikes inflict a heavy civilian toll.
Tawhid wal Jihad has declared loyalty to Osama bin Laden's al Qaeda and has claimed responsibility for beheading several foreign hostages. It has not said it is holding Margaret Hassan, who was abducted on Tuesday on her way to work at the aid agency Care International, whose operations she headed in Baghdad.
Hassan, who holds Iraqi, British and Irish citizenship, made a tearful plea for her life in a video broadcast on Friday. Hassan's husband, Tahseen Hassan, and Care International made separate appeals for her release.
"It is painful to see my wife cry. That image saddened and worried her friends and loved ones," Hassan said on Al Arabiya television.
"I ask you in the name of Islam and Arabism, and during the holiest Muslim month for my wife to return to me," he said. "Margaret is an Iraqi citizen and has lived here for over 30 years. She considers Iraq her home and loves it and that is why she dedicated her life to helping her people in Iraq."
Groups working with Care, from hospitals to water projects, plan a protest in Baghdad on Monday demanding Hassan's release.
The Army of Ansar al-Sunna militant group said it had beheaded an Iraqi man it accused of collaborating with US forces and posted pictures of the killing on the Internet.
In the video, Hassan urged Britons to press their government to withdraw British troops and not move them to Baghdad.
The video surfaced a day after Britain said it would move 850 troops from southern Iraq to an area near Baghdad, to cover for US forces likely to be sent to attack rebels in Falluja.
The US military is widely believed to be preparing for an assault on Falluja, in line with a pledge by the US-backed interim government to retake all rebel-held cities to enable all Iraqis to vote in nation-wide elections scheduled for January. But the interim government said it had resumed talks with Falluja leaders designed to find a peaceful solution.
About 18,000 armaments were handed over in a recent weapons-for-cash programme in Baghdad's Sadr City, Deputy Prime Minister Barham Saleh announced Saturday, calling the process a "great success".
"We have spent close to five million dollars on 9,000 anti-tank mines, 2,000 land mines, 2,000 Kalashnikovs, more than 1,000 rocket launchers, more than 2,000 anti-tank missiles," he told a press conference adding that more than 1,550 mortar shells and nearly 600,000 bullets were also handed in.
"The programme was a great success and the government is looking to repeat it in other parts of the country," he said.