(CNN) -- A gunman believed to be an Afghan soldier killed a British service member Monday, when he opened fire on ISAF and Afghan soldiers, according to the UK Ministry of Defence.
The "insider" attack occurred on a patrol base in the Nahr-e Saraj district of Helmand province. The victim was part of an engineer's regiment, MoD spokesman Tom Bennett said in a statement. Six other ISAF soldiers were wounded in the attack, another MoD spokesman said.
The term "insider" refers to strikes by Afghan National Army soldiers, police or by militants wearing their uniforms on members of NATO, with whom they are working together.
"Next of kin have been informed," Bennett said. The soldier's family has asked that no further details be released for 24 hours.
More than 50 people were killed in Afghanistan in similar attacks last year. The Afghan government calls the killings acts of terrorism.
Such attacks have triggered concerns about the stability of Afghan security forces ahead of planned NATO withdrawals in 2014.
In early October, an attack by an Afghan solider in Wardak province turned into an exchange of fire between U.S. and Afghan troops.
CNN's Alexander Felton contributed to this report.