A British royal marine has been killed in Afghanistan battling Taliban fighters.
US Protection and Investigations (USPI), based in Texas, is one of the biggest security firms working in Afghanistan. It has operated there since 2002. It employs 45 expatriates and hundreds of Afghans.
Qari Mohammad Yousuf, a spokesman for the Taliban, told Reuters news agency that the bomber was a member of the group.
About 105 suicide bomb attacks this year have killed nearly 250 people, most of them civilians, according to the Nato force in Afghanistan.