A gunman wearing an Afghan army uniform has shot and killed a British soldier in the latest in a spate of insider attacks that are fracturing the trust between Nato and Afghan forces.
Separately, officials said 11 Afghan civilians were killed by land mines on Sunday in the east and south.
The Ministry of Defence confirmed that the insider attack had claimed the life of a soldier from the Royal Scots Borderers, 1st Battalion The Royal Regiment of Scotland. It said the soldier was shot by an individual wearing an Afghan army uniform at his base in the Nad Ali district of Helmand province.
The serviceman was not named, but the MoD said his next of kin had been informed.
Mohammad Zarak, a spokesman for the governor of Helmand province, said the shooting took place after an argument broke out between an Afghan soldier and service members of the US-led coalition forces.
Coalition figures show that at least 60 service members have been killed and others wounded this year in about 45 insider attacks, where members of the Afghan security forces or insurgents dressed in their uniforms turn their guns on US and allied troops.
The insider attacks have raised questions about how effectively the allied forces can train the Afghans to take over security of their country by the end of 2014. They have also further undermined public support in Nato-member countries for the 11-year war and increased calls for earlier withdrawals.
In London, General David Richards, head of Britain's armed forces, described the insider attacks as a "very effective" Taliban tactic.
"They're very good at playing on our minds because of the impact it has in the minds of [ordinary people] and many people who are of influence, including our politicians," Richards said.
Meanwhile, roadside bomb killed three men, two women and a baby in the Khost province of eastern Afghanistan, the deputy provincial police chief, Youqib Khan, said. Their vehicle hit the bomb as they were returning from a hospital.
Three other civilians were killed when their vehicle detonated a land mine on the road between Helmand and Kandahar provinces, a government statement said.
Also in the south, two civilians were killed when they walked over a land mine in the Khakrez district of Kandahar province, said Ahmad Jawed Faisal, a spokesman for the provincial governor.
The United Nations says homemade bombs continue to be the weapons that have killed the most civilians in the war.