The soldier was on a multinational patrol in Maysan province in the south of Iraq when he was hit by small arms fire. He was serving with the 1st Battalion, the Highlanders in the 7th Armoured Brigade, which was visited by Tony Blair during a trip to Basra before Christmas. His death prompted renewed demands for Britain to prepare a timetable for early withdrawal of troops and for a fresh inquiry into Mr Blair's conduct over the war.
The Ministry of Defence said: "It is with very deep regret that we can confirm that one UK soldier from the 7th Armoured Brigade serving with the 1st Battalion, the Highlanders, subsequently died of his injuries. There were no other injuries to UK service personnel." The soldier's family has been informed.
The soldier's death intensified pressure at Westminster for an inquiry by a committee of seven Privy Councillors into the Prime Minister's handling of the Iraq war and the use of intelligence reports to boost public support for the invasion. Leaders of a cross-party group calling for Mr Blair to be impeached will meet tonight at Westminster to discuss their tactics.
They believe they will be able to persuade either the Liberal Democrats or the Conservatives to allocate time for a debate and a vote in the Commons in mid-March, to coincide with the third anniversary of the Commons vote that endorsed military action in Iraq. Among the 122 MPs who have signed the motion are the former international development secretary Clare Short, who resigned from the Cabinet over the war; Peter Kilfoyle, the former defence minister; and the former Conservative minister Douglas Hogg. Adam Price, the Plaid Cymru MP, said 22 Labour MPs and more than 50 Liberal Democrats had signed the motion.
"There is a constitutional issue over how we balance the power of the Prime Minister and a small group of people around him, with Parliament. It predates Blair but now is the time for Parliament to stand up and be counted and say we need a full inquiry.
"We have to learn the lessons from this wrong-headed invasion. We have to stop this happening again, whether it is Iran or Syria or somewhere else." He said the calls by General Sir Michael Rose, the British UN commander in Bosnia, for Mr Blair to be impeached had strengthened the campaign for a inquiry.
A former Labour minister said: "If we had not gone into Iraq, we could have put more resources into sorting out Afghanistan. It has been a complete disaster. The sooner we get out the better. We need a clear timetable for withdrawal."
Alex Salmond, leader of the Scottish National Party, said more MPs would put their names to the motion. "It will strengthen the case for impeaching Tony Blair and fully investigating his conduct in the run-up to the war in Iraq," he said.
Mr Blair returned from Basra impressed by the ability of the Iraqi forces to take over their own security. However, he received pessimistic reports about the Iraqi police force, which it is feared has been infiltrated by insurgents.
He gave strong signals while he was there that British troop reductions would begin in the coming months. Donald Rumsfeld, the US Defence Secretary, announced in December that 7,000 US troops would be withdrawn from a total deployment of more than 138,000 personnel. British ministers have resisted setting out a timetable because they fear that it would increase attacks by insurgents.