Two NATO soldiers and an Afghan policeman were killed in a battery of attacks that coincided with a NATO summit where world leaders called for extra troops to fight a spiralling Taliban insurgency.
Besides this attack on Tuesday, two other soldiers with the NATO-led International Security Assistance Force (ISAF) and five Afghans were wounded in the day's violence, which a NATO spokesman said was intended to "shake the will" of the alliance's leaders.
Afghan police, meanwhile, said that scores of alleged Al-Qaeda militants stormed a checkpoint on the eastern border with Pakistan, sparking an hour-long battle that left at least two rebels dead.
The 37-nation ISAF did not release the nationalities of any of its casualties. It always waits for the home nations to make this announcement.
The soldiers who were killed were in a patrol that was blasted by an explosive device in Logar province, near the capital Kabul, the force said. Another was wounded, as was an interpreter.
Most of the troops in Logar are US nationals, who make up about half of the 122 foreign soldiers now killed in action in Afghanistan this year.
The strike followed hours after a suicide bomber blew up a car near an ISAF convoy in Panjwayi, a Taliban stronghold in the southern province of Kandahar, from where the extremist movement rose to seize power in 1996.
The Taliban claimed responsibility for the attack, similar to around 100 suicide blasts in Afghanistan this year that reflect the influence of other world Islamist groups on the militia.