A suicide bomber drove his explosives-laden car into an armored NATO vehicle as the convoy was passing a bridge, tossing the military vehicle into a ravine below and destroying the bridge, said Zalmai Afzali, a spokesman for Kandahar's governor.
The attack happened near the Kandahar airfield, the second-biggest military base for US and other NATO troops in the country after Bagram near Kabul, said Fazel Ahmad Sherzad, the deputy provincial police chief.
The attack killed four Afghan civilians and wounded another, the Interior Ministry said.
A spokesman for the NATO-led International Security Assistance Force (ISAF) in Kabul confirmed that one ISAF soldier had been killed in the attack but did not reveal the soldier's nationality. The spokesman asked not to be named, citing alliance policy.
Afzali said that according to information provided by Afghan security forces on the ground, four NATO soldiers were also wounded in the attack.
Speaking by phone from an undisclosed location, Taleban spokesman Qari Mohammad Yousif Ahmadi claimed responsibility for the attack and said 11 foreign soldiers were killed in the bombing.
Separately, one civilian was killed and 16 other people, including nine Afghan police officers, were injured Monday in a car bombing in Kandahar city, the Interior Ministry said in a statement.
The vehicle packed with explosives had been left inside the parking lot of the main police headquarters in the city, Afzali said.
In another incident, two NATO soldiers were killed in an attack in western Afghanistan, while another ISAF service member was killed in a small arms attack in southern region, ISAF said in a statement.
Both attacks happened on Monday.
The military did not disclose the soldiers' nationalities, nor did it say where exactly in the regions the incidents occurred.
More than 100 NATO soldiers have been killed in Afghanistan so far this year, according to ICasualties.org, an independent website that tracks military casualties in Afghanistan and Iraq.
Monday's attacks came a day after 11 Afghan civilians, including two children and two women, were killed when their vehicle was blown up by a roadside mine in neighboring Helmand province.
President Hamid Karzai condemned the Helmand attack Monday and called it "an inhumane and un-Islamic act," the presidential palace said in a statement.
A total of 15,000 NATO and Afghan troops are taking part in a major offensive in Helmand. That operation has made slow progress into its third week against continued resistance by Taleban fighters.
US and NATO officials said the Helmand offensive was a prelude to a larger operation in Kandahar. About half of an additional 30,000 US troops being sent to Afghanistan by this summer are to be deployed in and around Kandahar province.
Kandahar and Helmand are Taleban strongholds and have been the center of its insurgency in the past eight years. Kandahar is the birthplace of the Taleban movement and was the headquarters of its leader, Mullah Omar, from 1996 to late 2001 when the Taleban's government was overthrown in a US-led offensive.
