At least 17 people have been killed in two bomb attacks in southern Afghanistan, officials say.
The explosion occurred outside the police headquarters
A suicide bombing in Kandahar city killed the attacker and 12 others, most of them policemen, officials said.
Eleven others were hurt in the blast outside police headquarters. A spokesman for the ousted Taleban said they carried out the attack.
In Farah province, a roadside bomb killed four, including two foreign engineers, a Turk and an Indian.
Officials said the engineers' Afghan driver and Nepalese guard also died.
Last week, fierce fighting between troops and Taleban fighters left at least 25 dead in southern Afghanistan.
Wave of attacks
A Kandahar city resident told the BBC the whole area had shaken with the force of Tuesday's explosion, and then described seeing bodies lying on the ground outside the heavily-protected police base.
The bomber apparently tried to drive into the complex on a motorcycle before setting off the explosion, reports say.
A doctor at the hospital told the AFP news agency that 10 policemen were among those killed and five of the wounded were also policemen.
A spokesman for the Taleban, Qari Mohammad Yousuf, called news agencies to say his group was behind the attack.
"The Taleban did this suicide attack. We will pursue these kind of attacks against government or coalition forces," the Associated Press quotes him as saying.
2 February: Three killed by attacker in south-eastern city of Khost
16 January 2006: Two attacks in Kandahar province kill 24 people
15 January 2006: Canadian diplomat and 2 Afghan bystanders killed in Kandahar
5 January 2006: 10 killed in Tirin Kowt, Uruzgan
November 2005: 3 civilians killed in Kandahar
September 2005: 12 killed outside Afghan army base in Kabul
May 2005: 3 killed in Kabul internet cafe
June 2005: 20 killed in Kandahar mosque
President Hamid Karzai condemned the attack which he blamed on "enemies of Afghanistan".
"Today's heinous act of terrorism is against the values of Islam and humanity," a statement said.
Meanwhile, in south-western Farah province, officials said the engineers' vehicle had been targeted by a remote-controlled bomb.
They had been working on a road linking Farah with the main road between Herat in the west and Kandahar.
The attacker is thought to have escaped on a motorbike.
Correspondents say such violence, including suicide bombings, has become more common in southern Afghanistan.
There has been an upsurge in violence in recent months, coming as the US plans to hand more responsibility for security in southern Afghanistan to its Nato allies.
Last year, attacks mainly in southern and eastern Afghanistan left more than 1,400 people dead. It was the country's bloodiest year since US-led forces ousted the Taleban in late 2001.