Intelligence officials believe the continuation of Nato supplies via the tribal area could be the main reason behind the bombing of Friday congregation in Jamrud Tehsil of Khyber Agency. "Our investigators are probing into the bombing keeping in view the recent threats by militants," a security official told The News here on Saturday. "The militants have recently been threatening of such attacks if the Nato supplies via Khyber Agency are not stopped by the government," he said.The official said the second reason of the attack could be the ongoing operation in Bara Tehsil of Khyber Agency. The third reason might be the arrest of some persons for links with the attack on the Sri Lankan cricket team in Lahore, he added.