Five more US soldiers have been killed in Afghanistan, sending Nato's death toll to 11 in 24 hours.
Four soldiers belonging to the International Security Assistance Force (Isaf) were killed by a bomb in southern Afghanistan, Nato said.
Another US soldier died in a separate attack also in the south of the country.
It comes a day after three US soldiers and five Afghan civilians died in a suicide attack in Kandahar province.
The latest deaths came as a major manhunt was under way in Helmand province for the rogue Afghan soldier who killed three British soldiers on Tuesday.
So far in July, 45 international troops have died in Afghanistan, 33 of them from the US. June saw more than 100 international troops killed - the bloodiest month of the nine-year-old war.
"We are in the toughest part of this fight," Isaf spokesman Brig Gen Josef Blotz told reporters.
Co-ordinated attack
Late on Tuesday a suicide bomber detonated explosives at the gate of the headquarters of an elite Afghan police unit in Kandahar. Minutes later, insurgents opened fire with machine guns and rocket-propelled grenades.
Three US soldiers, an Afghan policeman and five civilians died in the attack.
Isaf said that Afghan police backed by international forces fought back "and prevented insurgents from penetrating the compound perimeter".
The Taliban later admitted they were behind the attack.
Insurgents have stepped up attacks on government targets in Kandahar - the spiritual birthplace of the Taliban - as US reinforcements are poised for an expected Nato offensive in the city, which is.
The three British soldiers who died on Tuesday were serving with 1st Battalion, The Royal Gurkha Rifles, in Nahr-e Saraj.
Nato said it was using every "asset" within its power to find the Afghan soldier responsible and those who may be helping him.
Afghan President Hamid Karzai has vowed a full investigation into the shooting.
One of the three was shot and the other two were killed by a rocket-propelled grenade, the BBC understands.
Nato soldiers are increasingly fighting alongside their Afghan counterparts as the West tries to transfer responsibility for security ahead of a gradual withdrawal starting next year.
The Afghan interior ministry said another nine civilians were killed in Helmand province on Tuesday when the minivan they were travelling in was hit by a roadside bomb.
Bombs, known as improvised explosive devices (IEDs), are a common weapon of the Taliban.