Kingsman Alex Green (l) and Marine Thomas Curry died in combat
A British soldier killed in Iraq and a British marine killed in Afghanistan have been named by defence officials.
Kingsman Alexander Green died while on duty in Basra and Marine Thomas Curry was killed during operations in the southern province of Helmand.
Defence Secretary Des Browne said he was "greatly saddened" by the deaths.
The Ministry of Defence said Marine Curry, who was 21 and from east London, had died in a mission clearing Taleban positions at Kajaki, Helmand province.
Brigadier Jerry Thomas, commander of the UK Task Force in Afghanistan, said: "I send my sincere and heartfelt condolences to his family and to his friends.
"They have lost a much loved member of their family and a good friend and my thoughts are with them at this difficult time."
Marine Curry joined the Royal Marines in May 2005 and was awarded the Commando Medal during his initial training for showing qualities of "unselfishness, leadership, determination, and cheerfulness in the face of adversity".
An MoD spokesman said: "In typical fashion, Marine Curry was leading his comrades courageously from the front when he came under enemy fire, whilst in the process of clearing an enemy compound."
Kingsman Alex Green, aged 21, from Warrington and with the 2nd Battalion The Duke of Lancaster's Regiment, died as a result of injuries sustained from small arms fire whilst on a mission in the Hayy Al Muhandisn district of Basra City.
He was a father who leaves behind a two-year-old son.
The MoD said Kingsman Green had been spotted by colleagues and commanders as a "professional soldier" with "leadership and command potential".
His family said in a statement: "Alex loved the Army and the services. It was all he had wanted to do.
"He was living his dream. He was proud of being in the Army and doing his duty."
Marine Curry, who was serving with Plymouth-based 42 Commando, was killed during running battles with Taleban fighters.
The British troops crawled up a hill in the early hours of Saturday morning to launch an attack which left 16 suspected insurgents dead.
Nato forces have been fighting running battles with the Taleban
Nato commanders said the insurgents, who were hiding out in mud-brick compounds, had been disrupting planned work on a nearby dam project.
The British camp in Kajaki had also regularly endured mortar attacks from the compounds, military officials said.
They added that the decision to go after the militants was made after watching them for almost a month.
Mr Browne said his "thoughts and sincere condolences" were with both servicemen's families, friends and colleagues "as they come to terms with this terrible loss".
Earlier this week British troops killed up to 100 Taleban fighters as they destroyed a key base in Helmand province.
It was described as the UK Task Force's biggest pre-planned operation in the area to date.
There are currently 6,000 British troops in Afghanistan, with 1,000 based in the capital, Kabul, and 5,000 in Helmand.
In Iraq, there are 7,100 members of the British armed forces based around Basra in the south east of the country.
The last soldier to die in Iraq was Sergeant Wayne Rees, 36, who was killed in a road accident in rural Maysan province on 7 January.