KANDAHAR: Thirty-five people were killed in a Taliban assault on Kandahar described by rebels as a pre-emptive response to Western plans to eradicate them from the strategic city.

A series of massive explosions rocked the southern city late Saturday in what appeared one of the biggest coordinated assaults by the militants since their insurgency began more than eight years ago.

The governor of Kandahar province said he had requested more troops to help secure the city from further attacks by the Taliban, who regard it as their spiritual centre.

Interior ministry spokesman Zemarai Bashery said the attackers aimed to blow open Kandahar's prison and free its inmates, including militants.

He said the dead comprised 13 police officers and 22 civilians, and that another 57 people were injured.

The attack came as tens of thousands of extra troops are arriving in Afghanistan as part of a new counter-insurgency strategy aimed at concluding the US-led war on the Taliban.

The injured comprised 40 civilians -- among them six women and three children -- and 17 police officers. Forty-two houses close to the city's prison and its police headquarters were destroyed or badly damaged.

"Initial information shows that after the prison attack the enemy attacked locations and routes that end up at or are en route to the prison in an effort to prevent police from going and securing the prison," Bashery said.

President Hamid Karzai branded the perpetrators "enemies of Islam and Afghanistan".

"Those who do not respect Islamic values and act against them no doubt will be cursed by God and will go to hell," he said in a statement.

The city was hit by five blasts at 8:00 pm (1530 GMT) on Saturday. The first, caused by a huge suicide car bomb, occurred outside the prison and was followed by a similar blast outside provincial police headquarters.

Three other explosions were probably also suicide attacks, Bashery said.

"Most of the police casualties were outside the police headquarters where officers had stopped and surrounded the vehicle laden with explosives as it detonated," he said.

Early Sunday police seized eight explosive-packed suicide vests and three rockets from a house near the prison. The Taliban plan appeared to be to first break into the prison, then use suicide vests and rockets to burst open cells and free prisoners, Bashery said.

A Taliban spokesman, Yousuf Ahmadi, told AFP the attack was a response to comments by the commander of foreign forces in Afghanistan that Kandahar would be targeted in military efforts to eradicate the Taliban.

Kandahar was the Taliban's base during their rule of the country, which ended with the US-led invasion in 2001.

"This was an answer to General (Stanley) McChrystal, who announced Operation Omaid in Kandahar," Ahmadi said, using the name of the battle plan.

"This was to sabotage the operation and to show we can strike anywhere, any time we want."

Kandahar governor Turyalai Wisa said at least 10 people attending a wedding party were among the dead. Rescue workers were still searching the rubble.

He told reporters he had asked the Kabul government to send more forces to improve security.

"We have asked the central government to send us more security forces, especially intelligence workers, and they have accepted our request in principle," he said.

Up to 1,000 Taliban inmates escaped from Kandahar's Sarpoza prison in June 2008 after a suicide attack blew open the gates and destroyed the walls.

Another explosion took place early Sunday close to the Kandahar office of a Japanese construction company, injuring five employees -- four of them Pakistanis and one an Afghan.

The first major offensive of the current war strategy is taking place in Helmand province, neighbouring Kandahar province.

Visiting Afghanistan last week, US Defense Secretary Robert Gates told troops to brace for a tough fight as generals lay their plans to battle the Taliban in Kandahar.