A top US army officer said on Sunday he did not have confidence in a hand-held device used by Iraq's security forces to detect explosives and stop suicide bombers passing through checkpoints.

Major General Robert Rowe told reporters in Baghdad he was at odds with Iraqi officials on whether the ADE 651, a pistol-shaped gadget sold by a British firm which uses an antenna and is known as the "magic wand," worked.

"We do not agree on the technical capability of the device that is used here widely by the Iraqi forces," said Rowe, referring to the chief of the interior ministry's directorate for combating explosives, Major General Jihad al-Jabiri.

Security at checkpoints is especially sensitive in the wake of twin bombings at government offices on October 25 that killed 153 people and wounded 500. The attacks were claimed by a group linked to Al-Qaeda.

The bombers managed to convey almost two tonnes of explosives into the heart of the capital in what was a major blow to confidence in Iraqi security amid fears of political violence in the run-up to a general election in early 2010.

Rowe, director of the US army's training and advisory mission in Iraq, was quoted Tuesday in a New York Times report as saying: "I have no confidence that these work," when talking about the ADE 651.

Jabiri in the same article defended the gadget, reputed to cost between 16,500 and 60,000 dollars each and used at hundreds of checkpoints, and said "whether it's magic or scientific, what I care about is it detects bombs."

The ADE 651 uses a series of interchangeable cards said to be able to detect explosives and weapons. A police officer or soldier will walk along the side of a vehicle and the antenna will be drawn toward suspected contraband.

However, substances as diverse as perfume and metal tooth coatings are known to artificially trigger its sensors.

Rowe, who on a previous tour of Iraq served as an infantry brigade commander, said he preferred more traditional methods used to spot explosives.

"I am unaware and we have not been able to find for our forces an assured, highly probable technological solution that allows us to detect explosive devices," he said.

"From a distance, the best capability is highly trained soldiers and policemen attempting to recognise habits that might give you a reason to look closer. Much like when you go to an airport and your briefcase is swabbed."

He also said sniffer dogs, baggage screening machines, vehicle scanners and closed circuit television systems could be used more effectively.

A major consideration for Iraqi police is striking a balance between checkpoint security and sufficiently fluid traffic flow to allow people to go about their business with minimal disruption.

Vehicle checks using the ADE 651 take only a few seconds whereas a dog search will take several minutes.

"It is a difficult issue," Rowe added. "All over Baghdad and other cities there are people trying to get to work and those checkpoints are there to secure the population. This is the tension of an open society."

The October 25 attacks led to a dramatic increase in the overall death toll in Iraq for the month, with twice as many violent deaths than in September.

Statistics compiled by the defence, interior and health ministries showed 343 civilians, 42 police and 25 soldiers were killed last month, with only the military figure falling from September.

The figures were markedly higher than the previous month, which saw 203 people die as a result of violence, the lowest death toll since May, offering cautious optimism that security was improving.