A suspected suicide bomber has killed at least 10 people in southern Afghanistan, in an attack coinciding with the swearing in of Hamid Karzai, the Afghan president, for a second five-year term.

The bomber blew himself up in a busy market near an Afghan security forces convoy in Uruzgan province on Thursday, local police said.

"Ten civilians were killed and 13 others were injured," Mohammad Gulab Wardak, the Uruzgan deputy police chief, told the AFP news agency.

The dead were all civilians, including three boys aged between 12 and 14, local officials said.

Zemari Bashary, the interior ministry spokesman, said the bomber had detonated his explosives when a policeman tried to stop him.

It was the second attack of the day, following a car bomb attack that killed at least two US soldiers in Zabul province.

Ghulam Sarwar, an Afghan army colonel, said that a suicide car bomber detonated his explosives outside a military base in the Shah Joy district of Zabul province.

There was no immediate claim of responsibility for either bombing.