Three British soldiers have been killed by a roadside bomb in the southern Iraqi city of Basra.
The deadly bomb blast left a crater in the ground
A military spokesman said a fourth soldier was seriously injured in the attack at about 0100 local time on Thursday in the Al Antahiya district.
Two soldiers were from the Third Battalion, the Royal Regiment of Scotland, and the other from the Second Battalion, The Royal Welsh Regiment.
British soldiers are soon to be moved to Basra airport, the BBC understands.
World affairs correspondent Paul Wood said an official announcement about what he called the "dangerous retreat" would not be made until after the event to reduce the risk of attacks from insurgents.
And the BBC understands that British soldiers are expected to move from Basra city altogether to the airport "in the next few weeks over a single weekend".
Our correspondent said the military plan over the next 12 months was to reduce the number of British troops at Basra airport from 5,500 to just 1,500, although he cautioned that this could be changed by surprise political announcements.
A US official told him that this would have a "seismic" effect, in spite of the fact that the US has some 160,000 troops in Iraq.
The soldiers who were killed on Thursday had left their Warrior armoured vehicle in the south-east of Basra when an improvised explosive device was detonated.
The BBC's Jim Muir in Baghdad said the troops were returning to their base at Basra airport after carrying out a re-supply mission at their Basra Palace base.
A British military statement said: "It is with deep regret that we can confirm that three soldiers were killed by an improvised explosive device this morning."
The injured soldier is being treated at a military field hospital in Basra.
Maj Gell told BBC Radio Five Live: "It would be wrong to say incidents like this will not have an effect and morale from soldiers will, of course, take a knock.
There are around 5,500 British troops serving in Iraq
"All of us cope with death in different ways.
"As individuals, we all get deeply affected, but we all appreciate there is a job to be done, and service personnel are professional, very resilient, and we recognise that we have a task to do and we'll do that task well."
He said the number of insurgent attacks in Basra had peaked at the end of February, fallen, and was now rising again.
"We believe this to be in part because of our success against rogue militia who are trying to destabilise the situation," he said.
The deaths take to the total number of UK troops killed in Iraq since hostilities began in 2003 to 156.