"We claim responsibility for the Islamabad suicide attack. It was in retaliation for a drone attack in Orakzai," said TTP commander Hakimullah, Taliban chief Baitullah Mehsud's deputy.
"We have shown enough restraint. Previously, we were striking once in three months, but from now onward we will go for at least two suicide attacks a week," he added.
"In Islamabad we have been successful to hit our target and we will launch more attacks in retaliation for drone attacks," he said.
Most of the militant attacks in Pakistan occur in the northwest, where the Taliban and al-Qaeda have strongholds from which they plan strikes on US and NATO forces across the border in Afghanistan.