The NATO command in Afghanistan says one international solder has been killed by a person in an Afghan army uniform, in the latest incidence of what officials call “insider attacks.”

The International Security Assistance Force said early Tuesday that the attack occurred Monday in southern Afghanistan. It said the incident is under investigation, but gave no other details.

Reuters news agency quotes police officials as saying the attack took place in Helmand province, where mostly British and U.S. troops are based. It said a British soldier was killed and six more British troops were wounded.

“Insider” attacks have been on the on the rise in Afghanistan, leaving more than 60 foreign troops dead in 2012.

Monday's attack also came as Afghanistan's President Hamid Karzai and U.S. President Barack Obama prepared to meet in Washington later in the week for talks on the long-term security agreement between the two nations.