Twenty people have been killed in a suicide bombing in a crowded market in southern Afghanistan, police say.
Thirteen more were injured in the blast in Dihrawud in Uruzgan province.
The bomb could have gone off prematurely as the bomber waited for a military or police convoy to attack, said a deputy police commissioner.
On Wednesday, a UN report said the number of civilians killed in violence in 2009 was higher than in any year since the Taliban were ousted in 2001.
Civilian casualties rose by 14% in 2009 compared with 2008, the UN Mission in Afghanistan (Unama) reported.
This was the worst such incident in Afghanistan in months, and the dead were all civilians, says the BBC's Mark Dummett in Kabul.
Uruzgan is the home province of the Taliban's leader Mullah Omar.
As the insurgency spreads and more Western troops are sent to Afghanistan, 2010 is likely to be as bad as 2009 in terms of civilian casualties, our correspondent says.