Two Royal Marines have been killed in an explosion in southern Afghanistan, the Ministry of Defence has said. Their deaths bring the British military death toll in Afghanistan and Iraq combined to 300. The pair, from UK Landing Force Command Support Group, were taking part in a joint patrol with soldiers from Afghan security forces when their vehicle was struck by an explosive device in the Garmsir district of Southern Helmand. Commander Paula Rowe, of Task Force Helmand, said: "This is a tragic blow to us all in the task force, but our loss is nothing compared to that of their families and loved ones. Our thoughts and prayers are with them at this terrible time." The pair were operating as part of Task Force Helmand's Information Exploitation Group, which is responsible for gathering information to improve situational awareness and to gain an advantage over enemy forces. Brigadier General Richard Blanchette of the Nato-led International Security Assistance Force (Isaf) said: "Our deepest sympathies go out to their family, friends and fellow soldiers. "Their lives are irreplaceable to all of us who fight for the peace and stability of Afghanistan." Next of kin have been informed and have asked for a 24-hour period of grace before more information is released. The deaths bring the number of British services personnel killed in Afghanistan since operations began to 124, while 176 have died on active service in Iraq. Earlier, a suicide blast in eastern Afghanistan killed 11 civilians and a US soldier. The target of the attack, which also left 58 people wounded, was a convoy of allied troops on a road outside Jalalabad, the capital of Nangarhar province, near the Pakistani border. Interior ministry spokesman Zemarai Bashary said the bomber rammed his vehicle into the convoy as it went through a crowded market.