A Taliban suicide bomber on Friday assassinated a police commander and killed 16 others at a public bath in southern Afghanistan near the Pakistan border, the deadliest attack in months.
The militia claimed responsibility for the attack. Policemen, who are generally less well protected than soldiers, are common targets in the Taliban's nine-year insurgency against the Western-backed Afghan government.
The bombing underscored the perilous security in parts of the southern province of Kandahar, the Taliban's spiritual home, despite being the focus of the US-led military strategy to reverse their momentum.
It was the deadliest bomb attack in Afghanistan since a northern provincial governor and 19 other people were killed at a mosque in Takhar on October 8.
"At around 12:00 pm (0730 GMT) a suicide bomber blew up explosives strapped to his chest at a public bath in Spin Boldak," border police official General Abdul Raziq told AFP.
Apart from the head of the rapid reaction border police unit, who was killed, and two policemen who were wounded, all the other casualties were civilians, Raziq said.
The local government confirmed from provincial capital Kandahar that at least 17 people had been killed in the attack and that 23 people were wounded.
Shopkeeper Mujebullah, whose cousin was wounded in the attack, said the baths were in a crowded market and used by people to wash before attending the main weekly Muslim prayers.
"The public baths were destroyed. Lots of dead bodies were picked out of the rubble at the beginning and afterwards," he told AFP.
"Different people were killed in this explosion -- old people, even children," he added.
The administration released a statement saying the bomber had been targeting a police commander named Ramazan, who died in the attack.
Spin Boldak is a short distance from the border with Pakistan, where US officials say the Taliban and Al-Qaeda-linked insurgents use rear bases to plot attacks in Afghanistan and the West.
Taliban spokesman Yusuf Ahmadi told AFP by telephone that the militia killed the police commander and denied that civilians had been hurt, saying that when Ramazan used the public baths, he cleared everyone else out.
"Today is Friday (the weekly Muslim day of rest). There weren't any civilians inside," he told AFP, speaking from an unknown location.
The Taliban are fighting to bring down the Western-backed Afghan government and expel 140,000 US-led foreign troops.
US officials say an American-led military campaign in the south is make-or-break for the war, pinning their hopes on undermining the Taliban in its heartland and limiting the number of attacks such as Friday's bombing.
The US-led NATO force in Afghanistan said bomb attacks killed three of its soldiers on Friday, two in the east and one in the south.
It declined to identify the soldiers' nationalities. In 2010, 711 foreign troops were killed during the war, by the far the deadliest annual toll in the nine-year conflict.
Defence Secretary Robert Gates has ordered an extra 1,400 US Marines to southern Afghanistan in a move the Pentagon said would put pressure on the Taliban in order to pre-empt a traditional insurgent offensive in the spring.
Defence officials expressed hope that the extra troops would bolster areas recently cleared between Kandahar city and Helmand province.
There are about 97,000 American troops in Afghanistan and 45,000 from other countries. Officials said the new Marines would not push the total number of US forces above the limit of 100,000 authorised by President Barack Obama.
A year after ordering 30,000 more troops to Afghanistan as part of a last-ditch "surge" strategy designed to defeat Al-Qaeda and reverse the Taliban, Obama conceded last month that gains were fragile and reversible.
US commanders are under pressure to show clear progress in Afghanistan in 2011 so that at least a limited drawdown of American troops can begin from July, or else face fresh public doubts about the course of the war.