Kandahar, March 14 (DPA) Four suicide bombers attacked different parts of southern city of Kandahar Saturday, killing more than 30 people, and injured at least 40, officials said.

The main target of the coordinated attacks was Kandahar's main jail, which houses hundreds of Taliban militants caught during the anti-insurgency operation by Afghan and NATO forces, Ahmad Wali Karzai, President Hamid Karzai's younger brother said.

'I believe the attackers could not make their way inside the prison,' Karzai, who is the head of provincial council and currently visiting Kabul, told DPA.

The Taliban militants attacked the same prison in June 2008, breaching the prisons security barriers and freeing hundreds of inmates, mostly Taliban fighters.

Karzai said that dozens of people were killed and wounded in the attacks, but could not give any exact figures.

'More than 30 people, including three police officers, were killed in the attacks,' Abdul Jamil, a police officer said. He said more than 40 others, mostly civilians, were injured in the attacks.

'We received 25 dead bodies so far,' Mohammad Karim, a doctor in Mirwais Hospital, the main medical facility in country's second biggest city said.

At least two suicide bombers detonated their explosives near the police chief's residence and provincial council's compound in the western part of the city, Jamil said, adding that gun shots also rang out in at least two localities.

There was also an explosion near a wedding hall in the city, causing casualties among the guests, Mohammad Daoud, a local resident, who lives near the site, said.

The attacks in Kandahar, the birthplace of the Taliban movement and the main headquarters for their leader, Mullah Mohammad Omar, until late 2001, happens as the biggest-ever operation by Afghan and NATO forces in the neighbouring province of Helmand completed its first month Saturday.

Afghan and NATO officials have said that the operation in Helmand's Marjah is a prelude to a bigger offensive to take place in Kandahar in spring. The top NATO commander in the country, US General Stanley McChrystal has said that the operation would take place when additional US troops arrive in the region.

US officials have said that most of the extra 30,000 US troops to arrive in the country by summer will be stationed in Kandahar.

The Kandahar attacks come after a roadside blast earlier Saturday in southern Afghanistan claimed six lives, though it remained unclear if the dead were military or civilians.