KABUL (Reuters) -- A suicide bomber rammed a car into a United Nations convoy as it drove through a market in southern Afghanistan, killing a driver and two local doctors, UN officials and police have said.
Police said another 16 people were wounded in the attack, part of rising violence this year by the Al-Qaeda-backed Taliban in Afghanistan. The bombing occurred on a road in the town of Spin Boldak, on the border with Pakistan.
The doctors were working for the UN's World Health Organization on a polio vaccination campaign in the region.
"This attack was on innocent civilians working only for the people of Afghanistan, and is beyond comprehension." the UN Assistance Mission in Afghanistan said in a statement.
The Taliban claimed responsibility for the attack on their website.
The resurgent Taliban rely largely on suicide attacks and roadside-bomb blasts in their insurgency against President Hamid Karzai's government and the foreign troops backing it.
Nearly 3,000 people have died violently in Afghanistan this year, the bloodiest period since the Taliban's overthrow in 2001.
But fatalities among UN workers are rarer. The last UN staff member to be killed in Afghanistan was an Afghan driver killed in Kandahar by a remote-controlled explosion in April 2007, according to UN spokesman Dan McNorton.
In another attack on September 14, a roadside bomb killed a provincial official and two of his bodyguards after the device hit their vehicle in southern Zabul Province, an official said.
A British soldier was killed in an explosion on September 13 in Helmand, a province in southern Afghanistan where the Taliban remains strong. His death raises the number of British troops killed in Afghanistan to 120 since the 2001 U.S.-led invasion.
Late on September 13, militants killed seven police, including a district police chief, in Ghazni Province to the southwest of Kabul. A roadside bomb killed a provincial governor the same day near the capital.
The rising violence this year comes despite an increase in the number of foreign troops in Afghanistan to 71,000, prompting some Western politicians to warn of a slide back into anarchy.
The militants have expanded the depth and scope of their insurgency and enjoy safe havens in fiercely independent tribal areas of neighboring Pakistan.
The U.S. military conceded this month that it was not winning the fight against the Taliban in Afghanistan, adding that it would revise its strategy to hit militant bases inside Pakistan.
The head of Afghanistan's spy agency, Amrullah Saleh, said the revision of U.S. war strategy to involve hitting militants in Pakistan was a belated move, media reported on September 14.
Saleh said the Taliban's fugitive leader, Mullah Mohammad Omar, and Al-Qaeda chief Osama bin Laden were in Pakistan,
"Where can they go? They have no passport, the only place they can go is Pakistan," local media quoted Saleh as telling the BBC's local-language program.