There has been some debate about whether the bomb could have been a legacy one left over from the Soviet era in the 1980s or whether the armoured vehicle hit one of the Taliban's smaller improvised explosive device (IEDs).
The six soldiers, five from 3rd Battalion The Yorkshire Regiment and one from 1st Battalion The Duke of Lancaster's Regiment, were on a mounted patrol when their Warrior armoured fighting vehicle was caught in an explosion the British Ministry of Defence announced
today (Wednesday, March 7th). The incident happened on Tuesday.
They had been travelling as part of a two Warrior patrol when the vehicle was hit at a junction where a road travelling east from Gereshk meets another heading north to Lashkar Gah, the MoD said.
reports that this is the biggest loss of life in one incident since a Nimrod crashed in 2006 killing 14. It puts the number of British military deaths in Afghanistan since forces were deployed in 2001 at 404.
The last time a similar number of UK casualties was caused by IEDs was in the summer of 2009, when five British soldiers died in an IED blast. The device remains the deadliest weapon in the Taliban's arsenal. It is effective on a psychological level, as well as causing deaths and severe injury, and is relatively cheap and simple to manufacture.
Lieutenant Colonel Gordon Mackenzie, spokesman for Task Force Helmand, said: "I have the tragic duty to report that six soldiers are missing, believed killed, during a security patrol. The six soldiers, five from 3rd Battalion The Yorkshire Regiment and one from 1st Battalion The Duke of Lancaster's Regiment, were on patrol in a Warrior armoured fighting vehicle when it was caught in an explosion in the Task Force Helmand Area of Operations."
Details are still being confirmed and further information will be released in due course. The families of the soldiers have been informed.
Chief of the Defence Staff, General Sir David Richards, said: "I was deeply saddened by the news of this incident and that six soldiers are believed to have lost their lives doing what is a dangerous but important job. My thoughts and prayers at this difficult time are with the families of those affected by this tragic event."
He added: "This campaign has seen many personal tragedies and we owe it to those who have made the ultimate sacrifice to recognise that their courage and skill are visible in the ever more capable Afghan Army and Police. Increasingly the Afghans themselves are taking the lead in providing security across Helmand. This transition is allowing Afghans to gain the confidence to reject the Taliban and live normal lives."
General Richards continued: "The courage, fortitude and determination of those servicemen and women currently in Helmand are inspirational. They have not once wavered but, every day, mix the professionalism of which we are all so proud with deep commitment and determination.
"The support shown by the public towards our men and women continues to be a source of great strength for the Armed Forces. They feel strongly that they are protecting us all through their service in Afghanistan."
In the House of Commons, British Prime Minister David Cameron told MPs "every possible support" had to be given to a political settlement in Afghanistan and a clear message had to be sent to the Taliban that - whether UK troops or Afghan troops were there - they "will not win on the battlefield, they never win on the battlefield".
Mr Cameron said he had spoken to the UK's leading military officers, who had stressed the commitment of troops to "getting the job done".
He also said he would discuss the Afghanistan situation with President Barack Obama on his visit to the US next week to ensure they were "in lock step" about the importance of training up the Afghan army and police, and making sure all NATO partners had a properly co-ordinated process for transition.
Most UK troops are expected to be withdrawn from Afghanistan by the end of 2014, when 13 years of combat operations in the country are set to cease.
Tributes have already been made on Facebook
and also on the HM Forces website forum's Book of Remembrance