by Arif Ali

Pakistan on Thursday interrogated suspects over a gun, grenade and bomb attack that demolished a police building
and damaged intelligence offices as suspicion mounted against the Taliban.

A van packed with nearly 100 kilogrammes (220 pounds) of explosives in Lahore blew up and levelled the police building, partially damaging offices of Pakistan's premier Inter-Services Intelligence agency, investigators said.

Three attackers had stepped out of the van, opened fire and thrown a grenade. One of them was shot dead by guards. Seconds later the van exploded, killing the other two in the security nerve centre of the eastern city.

Officials said 24 people were killed and about 300 wounded. The government interpreted the attack as revenge for a month-long military offensive designed to eliminate the Taliban in the northwest Swat district and a website published a purported claim from an alleged Taliban splinter group.

A group called "Tehrik-i-Taliban Punjab" claimed responsibility in Turkish, in a statement posted on Turkish jihadi websites through an intermediary organisation, said US specialist Islamist monitoring group SITE.

The monitors quoted the group as saying the attack "targeted the 'nest of evil' in Lahore, and was a 'humble gift' to the mujahideen who suffer beneath the attacks of Pakistani forces in Swat".

A top Pakistani security official said that while a similar claim emerged over a Shiite mosque bombing that killed 22 people on April 5, investigators believed no such organisation exists.

"It is merely a deception. It is an extension of Tehreek-e-Taliban (TTP) of Waziristan," the security official told AFP on condition of anonymity because he was not authorised to speak.

Pakistan's most wanted man, Baitullah Mehsud, for whom the United States has posted a five-million-dollar reward, commands TTP from its stronghold in the tribal area of Waziristan, outside government control on the Afghan
border.

He claimed responsibility for an assault on a police academy near Lahore two months ago, threatening further attacks in Pakistan and in the United States in retaliation for US air strikes against Al-Qaeda-linked militants.

"TTP wants terrorists to strike in Punjab (Pakistan's most populous province) but does not have an organisational structure - Tehrik-i-Taliban in Punjab. There is no independent group like this," said the security official.

Suspicions are falling on TTP as the group behind Wednesday's attack but Lahore city police chief Pervaiz Rathore, when contacted, declined to go into details about lines of inquiry, saying only that investigations were underway.

Wednesday's bombing was the third deadly attack to rock Pakistan's liberal cultural capital since March, pointing to a widening net of Islamist violence that has killed more than 1,800 people across Pakistan in less than two years.

Pakistan had rounded up about a dozen suspects in connection with the bomb attack for questioning, a security official told AFP.

A senior police officer confirmed raids in and around Lahore, but said so far no breakthrough in the investigation had been made.

Funerals were held late Wednesday for 13 police officers who were killed in the attack. A 14th policeman, who was a Christian, was to be buried separately.

Pakistan's military has been locked in a month-long offensive against Taliban militants in the northwestern Swat valley, which the authorities say has killed about 1,200 extremists and sent 2.4 million people fleeing.

"Enemies of Pakistan who want to destabilise the country are coming here after their defeat in Swat," Interior Minister Rehman Malik told reporters.

On March 30, attackers armed with guns, grenades and suicide vests stormed a police training centre on the outskirts of Lahore, unleashing eight hours of gun battles and killing seven police cadets and a civilian.

On March 3, gunmen ambushed the Sri Lankan cricket team bus in Lahore, killing eight Pakistanis and ending hopes of the country hosting international sport in the immediate future.