Kandahar (Afghanistan): A day after seven UN staffs were killed by a mob in the worst attack on the world body in Afghanistan since the 2001 invasion in protests against a Quran burning in the US, ten people died on Saturday in new protests.

The fresh protests began in the centre of the main southern city of Kandahar and spread as police clashed with crowds marching towards the UN offices and provincial administration headquarters, witnesses said.

Police had fired into the air to try to deter thousands of protesters heading towards the buildings, a reporter at the scene said.

Smoke was rising from different parts of the city as protesters burned cars and tyres.

The provincial authorities said the protesters had damaged government and private buildings and torched vehicles.

Daud Farhad, a senior doctor in the city's main hospital, said the death toll had risen to 10. About 83 others were injured, including two members of the Afghan security forces, he said. Provincial authorities had earlier given a toll of nine dead and 73 injured.

Kandahar is the spiritual heartland of the Taliban, who have fought an insurgency against President Hamid Karzai's government in Kabul and its Western allies since they were ousted by the US-led invasion.

"Death to America" and "Death to Karzai" chanted the demonstrators. "They have insulted our Quran," shouted one.

A news freporter saw two unidentified bodies being removed by demonstrators in Chawk Saheedan, a central location where the protests started.

Zalmai Ayoubi, a spokesman for the provincial administration, said a bus and a girls' school had also been set ablaze.

He said that "destructive elements have entered the crowds and are trying to turn it violent". Ayoubi added that all the dead and injured were protestors.

The administration said 16 people, seven of them armed, had been arrested.

The protest came a day after seven UN foreign staff -- three Europeans and and four Nepalese guards -- were killed during similar demonstrations in the normally relatively calm northern city of Mazar-i-Sharif.

The Taliban claimed responsibility for the Mazar-i-Sharif violence following a battle lasting more than three hours in which part of the UN compound was burned down amid small-arms fire and explosions.

US President Barack Obama condemned the attack while UN Secretary General Ban Ki-moon said it was "an outrageous and cowardly attack".