BAGHDAD — The SAS was on standby to mount a rescue mission in Baghdad last night after five Britons were kidnapped in a raid by suspected Shiite militants.

Dozens of gunmen and vehicles apparently belonging to a paramilitary unit of the Iraqi interior ministry took part in an operation to snatch hostages from a government building in the heart of the Iraqi capital.

The exact number of those kidnapped was still unclear last night, with witnesses reporting that up to seven people were taken.

The Foreign Office confirmed that five Britons — a computer expert and four security contractors — were among those seized.

A spokesman said: “Officials from our embassy are in urgent contact with the Iraqi authorities to try to establish the facts and to secure a swift resolution.”

The uniformed raiders walked into the finance ministry building, just before midday. One man in a police major’s uniform shouted: “Where are the foreigners?” before the hostages were bundled into cars and driven off.

In Whitehall, the emergency response committee, Cobra, was meeting to coordinate efforts to bring about the release of the five men.

British officials said a crisis team had been assembled with police hostage negotiators, MI6 officials, and Arabic linguists preparing to fly out to Baghdad.

On the ground the crisis team will liaise with the SAS. Norman Kember, the 76-year-old Christian peace activist, was freed in an SAS operation in Baghdad last year. The elite Special Forces regiment maintains a rapid reaction unit in Baghdad on permanent high alert for any reports of British kidnapping.

Four of the five Britons, who have yet to be named, were private security contractors for the Canadian firm, GardaWorld.

They were protecting a computer consultant, who was working for the American-based consultancy BearingPoint and was at the ministry to give a presentation. The raid marked the first time that Westerners have been snatched from a government building.

The scale and degree of organization of the raid suggested that renegade Interior Ministry personnel were involved. The ministry, which is dominated by Shiite Muslims, has repeatedly been accused of harboring death squads. Suspicion also fell on dissident members of the Madhi army, the Shiite militia loyal to the firebrand cleric Moqtada al-Sadr.

[Meanwhile, 10 American soldiers died in roadside bombings and a helicopter crash on Memorial Day, the military reported yesterday, making May the deadliest month of the year for U.S. troops in Iraq.

The American deaths raised the number of U.S. forces killed this month to at least 112, according to an Associated Press count assembled from U.S. military statements.]