Security officials and workers at the site of the suicide car boombing in Lahore Wednesday

Pakistan's Interior Minister Rehman Malik on Wednesday blamed the Taliban for the attack outside the ISI headquarters in Lahore, saying the strike could be a retaliation of the Government's military offensive against the militant outfit.

"It appears to be a fallout of the ongoing military operations in Swat, Dir and other areas of NWFP," said Malik. There would be no let up in the crackdown on these "anti-national elements", he added.

"They want to destabilise Pakistan.

Threats have been held out by Tehrik-eTaliban chief Baitullah Mehsud," the Interior Minister told reporters in Karachi.

"We are in a state of insurgency. There is a war inside the country and there were two options before the Government... either to cave in... or to confront and crush them," Malik said. "We have opted to flush them out," Malik said and sounded a warning to radical groups to lay down arms as they had no other option left. The Government has geared up intelligencesharing with the provincial Government, the Interior Minister added.

The attack at the ISI headquarters on Wednesday that killed 35 and injured 390, is the third major strike to rock Lahore in less than three months, following the March 3 attack on the Sri Lankan cricket team and the March 30 attack on the Manawan police academy.

The attack came a day after Taliban spokesperson Maulvi Mohammad Omar threatened attacks across Pakistan if the military operation in Swat was not stopped. However, no group immediately took responsibility for the attack. According to reports, some suspects picked up in connection with the terror attack on the Lankan cricket team here being interrogated inside the ISI office when the blast took place.

The site is also close to the Lahore High Court where Jamaat-ud Dawa chief Hafiz Saeed, detained in the aftermath of the Mumbai terror attack, was scheduled to appear for a hearing on Wednesday.

Last year in March, some suspects involved in the Naval War College attack were interrogated at the Federal Investigation Agency building when a mini-truck loaded with huge explosives ran into it, killing 30 people, mostly FIA officials.