Four British servicemen were killed and three seriously injured in Basra yesterday, one of the worst days for UK forces since the start of the Iraq war.
The attack was on a boat, with Royal Marines and other personnel on board, which was on a routine patrol on the Shatt al-Arab waterway, a vital lifeline for Iraqi insurgents and part of the volatile border with Iran.
The boat was attacked as the nation mourned its war dead on Remembrance Sunday, amid continuing debate about an exit strategy from Iraq, which is sliding further into violence and anarchy. The latest deaths, bringing the number of British soldiers killed in Iraq to 125, is certain to lead to renewed calls for Tony Blair to lay out a timetable for withdrawal.
The attackers used an improvised explosive device (IED) - the first time insurgents have successfully used such a weapon on a boat. According to defence sources, the bomb is likely to have been placed on a pontoon on the edge of Basra City where the Tigris joins the Euphrates. It was detonated as the boat went past.
The casualties represented one of the heaviest losses suffered in a single incident. The injured soldiers were evacuated by helicopter to a medical facility at Shaibah logistics base. The condition of two of them was described as "very serious" and the other one as "serious".
Ten military personnel were killed when an RAF Hercules aircraft was shot down in Balad, north of Baghdad, last year, and five more died in the shooting down of a helicopter in Basra last May. Six members of the Royal Military Police were killed at Majr al-Kabir, in Maysan province in the immediate aftermath of the invasion.
British military spokesman Captain Tane Dunlop said: "At the moment we have our ammunition technical officers and weapons intelligence experts analysing what has happened.
"We do not have any details exactly on the positioning of the device at this time. Our response has been the response to all such events in that the first priority is to evacuate the casualties, which has been done. Also we shall be carrying out a follow-up operation to target those responsible."
The attack raises concern over the safety of British forces who have been carrying out regular patrols on the waterway which borders Iran and has been a strategic route for both smuggling and the insurgency.
The British and US governments have accused Iran of supplying sophisticated IEDs, known as "shaped charges", to Shia militias for use against allied forces - a claim denied by Tehran.
Colonel Mike Dewer, a military analyst, said it showed how sophisticated the enemy had become and to what extent the military has to be constantly on guard. "I would expect they would be a great deal more circumspect about how and when they use river transportation.
"All they can do is continue to vary the operations, vary the routes and hope, in that manner, to be one step ahead of the enemy," he said.
The attack was also the latest lethal example of renewed violence directed against British forces in southern Iraq by Shia insurgents. A soldier was killed last week when his base in Basra came under attack.
The two main Shia militia groups, the Mehdi Army led by the cleric Muqtada al-Sadr, and the Badr Brigade, have been involved in bitter internecine battles for the control of the south and its oilfields.
It was unclear last night which faction had been responsible for the Shatt al-Arab attack.
The Defence Secretary Des Browne said: "This terrible incident reinforces in our minds the sacrifice made by the brave men and women of our armed forces."
Biggest losses of the war
Since the invasion of Iraq in March 2003, 125 British armed forces personnel have died - 95 in action, the rest through accidents, non-combat injuries, illness or causes being investigated.
* 21 March 2003
Eight Royal Marines and four US soldiers died when a helicopter crashed in Kuwait.The victims, from 3 Commando Brigade, were the first British fatalities of the war.
* 22 March 2003
Six British servicemen and a US officer died when two helicopters from the aircraft carrier Ark Royal collided in mid-air in darkness over international waters in the Gulfas troops were being deployed to seize oilfields on the Faw peninsula in southern Iraq.
* 24 June 2003
Six Royal Military Police offficers were killed at a police station in Majar al-Kabir after a riot in the town. The men had been training Iraqi police officers.The soldiers had held out against a mob, thousands strong, for about two hours, isolated and alone after their radio was lost with their Land Rover.
* 23 August 2003
Three members of the Royal Military Police were killed in an ambush in Basra.The soldiers were travelling in early-morning traffic in an unmarked four-wheel-drive car when they were attacked by men armed with grenades, rocket launchers and automatic weapons.
* 30 January 2005
Ten servicemen were killed when a Hercules aircraft was shot down north-west of Baghdad.
* 6 May 2006
Five died when a helicopter on routine patrol crashed into a house in Basra, southern Iraq, apparently after being hit by a missile. The dead included Sarah-Jayne Mulvihill, the first British servicewoman killed by enemy action abroad since the Second World War.Reuse content