"Now he [Wali Karzai] is in Kabul; we did speak to him and he did not have much more information than that.

"The third explosion happened near the main prison in Kandahar. There was a forth explosion after that. Some reports say it was close to a mosque, others say it was close to the prison.

"The one in front of the prison was huge, some of the buildings there have collapsed. Rescue operations have to wait till sunlight to see if there are more bodies under the rubble. Because the explosion happened at 8pm local time most people were at home so we expect the death toll to rise.

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Al Jazeera's correspondent said among the victims were at least nine policemen and hospital sources said three children [were killed].

She said the aim of the attack was to inflict damage on the prison to allow prisoners to escape.

The prison was reinforced with cement blocks after a suicide attack in 2008 blew open the prison gates and freed hundreds of criminals and suspected Taliban fighters.

High alert

Kandahar hospital was put on full alert and appealed for blood donations.

The Taliban claimed responsibility for the series of attacks.

A statement on the group's website said the attacks were to serve as a "message" to General Stanley McChrystal, the Nato commander, who is planning an
operation in Kandahar against the fighters.

Kandahar is Afghanistan's third biggest city, after Kabul and Herat, and was the spiritual capital of the Taliban, who ruled Afghanistan from 1996 until their overthrow in the 2001 US-led invasion.

Remnants of the movement have regrouped to wage an increasingly deadly insurgency, which last year killed more than 500 foreign soldiers.