KANDAHAR, Afghanistan -- NATO's International Security Assistance Force said two of its soldiers were killed and two wounded in an explosion Sunday in southern Afghanistan.
NATO did not say which country the soldiers came from or where the blast occurred. Britain, Canada, the United States and the Netherlands all have a significant number of forces in the south.
Meanwhile, Taliban militants attacked a police checkpoint in a separate explosion early Monday in a dangerous region of southern Afghanistan, killing 11 policemen in the latest assault against the nation's vulnerable police force.
Insurgents opened fire on the police in the Arghandab district of Kandahar province, said deputy provincial police chief Amanullah Khan. Preliminary reports indicated that one of the policeman had links with the Taliban, he said.
Militants killed more than 925 Afghan police last year -- more than 10 percent of the country's 8,000 insurgency-related deaths documented by the UN.
Police make inviting targets for Taliban attacks. They have less training and less firepower than the Afghan army or NATO soldiers. They also tend to work in small teams in remote parts of the country where they can easily be overwhelmed by a small insurgent force.
Monday's ambush was the latest in a string of recent attacks on police in the south. Eight police were killed Saturday -- four while destroying opium poppies in Kandahar and four who were manning a checkpoint in Helmand. Seven police on the poppy-eradication force were killed April 7 in Kandahar.
US officials say police are the focus of Taliban attacks because they are the weakest link in the country's security chain. Taliban militants often suffer devastating losses when they attack US or NATO forces that have been stationed in the country since the 2001 US-led invasion that drove the Taliban from power.
They have also largely abandoned ambush attempts against the increasingly capable Afghan army.