No one questioned the dozens of gunmen in police uniforms who pulled up outside the Finance Ministry office in east Baghdad in broad daylight.

Bearing official-looking documents, the gang entered the building, where a British consultant and a team of British bodyguards were at work.

Minutes later — at the height of the US-led “surge” intended to bring security to the city — the Britons were gone, after what one Iraqi security official described as a “very organised” abduction, with some of the gunmen wearing police commando uniforms. Amid confusing early reports, there were indications that Germans may also have been seized.

Four of the Britons work for GardaWorld, one of many security firms guarding VIPs and coalition contractors. The fifth man was one such contractor, working for the company BearingPoint, which provides technical and computer advice to the Iraqi Government.

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The raid, on a Shia-controlled ministry building, represents the most brazen abduction of Westerners in Iraq since the 2003 invasion.

A ministry official who witnessed the kidnapping said that it had taken place as several computer experts were giving a lecture on organising electronic contracts. She said that another lecturer had escaped abduction because he was not sitting with the others. According to the witness, the gunmen entered the room led by a man wearing a police major’s uniform. “Where are the foreigners, where are the foreigners?” they shouted.

Another ministry employee said that she recognised one lecturer and two bodyguards among those who were taken.

The raid triggered a large security alert in the heart of Baghdad, with checkpoints hastily erected.

Some were official Iraqi police roadblocks, others hastily improvised barricades fashioned from plastic cones, wooden blocks and even the blackened engine parts of vehicles blown up in suicide bombings.

While Iraqis sweltered in long petrol queues and traffic jams, US Humvees rumbled past the queues with guns trained on anything that looked remotely suspicious.

Iraqi police questioned drivers while Iraqi army tanks and armoured personnel carriers stood beside major junctions, all part of the “surge” that has put thousands more US troops into Baghdad since February.

On the Shia-dominated eastern side of the River Tigris, it was not immediately clear who was behind the kidnappings. There were no immediate hostage demands or official claims of responsibility.

Some pointed the finger at al-Mahdi Army, the militia loyal to the Shia cleric Hojatoleslam Moqtada al-Sadr. Wissam al-Waili, also known as Abu Qadir, the Mahdi Army’s Basra commander, was killed in a gunfight with Iraqi special forces supported by British troops on Friday. Hojatoleslam al-Sadr urged Sunnis and Shia to unite against US-led forces.

Mahdi Army commanders in Baghdad, however, denied that the milita had anything to do with the kidnappings. “We called all our groups immediately afterwards and no one said they did it,” a senior Mahdi Army commander in the Iraqi capital told The Times.

“We called the Iraqi police in the area and they told us it was uniformed men speaking with Sunni accents,” he said.

However, far from condemning the abductions, the Shia commander welcomed them, saying that it was important for Sunnis and Shia to work together against the British and American occupation.

Further muddying the issue, hundreds of miles farther south, Abu Hussein, a Mahdi Army commander in Basra, insisted that the kidnappings were their work.

“It is not only a reaction but it is the end of the British here,” he said. “We will take revenge on the British. It is not just this operation but there will be more and bigger operations,” he told The Times.

Abu Mohammed, a senior official in a Sadrist office in Basra, added: “It is a reaction against the British behaviour and violence against our leaders . . . There will be more and bigger operations against them. In quality and quantity.”

In Baghdad Canon Andrew White, the vicar of St George’s church in Baghdad who heads the Foundation for Relief and Reconciliation in the Middle East, appealed for the men’s release. He said he knew the kidnapped Britons personally because their company had long offered its services “free of charge” to protect his organisation’s work building bridges across communities.

“I know these individuals. I eat with them every day, they look after me,” said Canon White, who has extensive experience in previous hostage negotiations across the Middle East.

“They are not just here to make money. They seriously want to make peace. They collect us from the airport, bring us to Baghdad, provide all our food and they have never taken one penny from us.

“We are trying to contact all of our Iraqi friends to find out who has them. The fact that they were taken from a Shia ministry by people dressed as policemen and using police cars is worrying. It shows you can’t trust anybody any more,” he said.

The German Foreign Ministry said it was checking reports that Germans had also been seized in the raid. “The embassy in Baghdad and all of the relevant offices have been alerted and are working swiftly to clarify the matter,” a ministry spokesman said.

Yesterday’s raid was the first reported kidnapping of foreigners since the Baghdad security plan began in mid-February and the first time Westerners had been taken from inside a government building.

Kidnappings in Baghdad are a daily occurrence, usually for ransom or political motives. Men in camouflage uniforms took dozens of Iraqis from the Higher Education Ministry in November.

More than 200 foreigners and thousands of Iraqis have been kidnapped since 2003, although there had been a recent lull in the taking of foreigners.

At least two Britons have been kidnapped and killed in Iraq since the March 2003 invasion. Kenneth Bigley, an engineer, was beheaded by his abductors in October 2004; a month later Margaret Hassan, an aid worker, was shot dead.

Paul Bigley, the brother of the murdered hostage, offered last night to speak to the captives’ families.

Not all kidnappings in Iraq end in tragedy. The British peace activist Norman Kember was captured in November 2005 and rescued by British special forces in March last year.

The suspects

Al-Mahdi Army Shia militia known to have kidnapped and released Westerners and accused of killings among Sunni population

Al-Qaeda in Iraq Followers of Osama bin Laden who see killing of hostages as part of continuing war. Have released filmed executions

Baathists Former Baathist security forces banned from employment after the invasion often kidnapped and released hostages for money. Have reduced activities since being allowed to return to work

Criminal gangs Kidnap and ransom for purely financial reasons. Unlikely to kill valuable hostages but will sell them to a militant group

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