Pakistani security forces have rounded up about two dozen suspected al-Qaida members using information from the network's third-in-command who was arrested this week.
Officials say raids are being carried out in several cities following interrogation of Abu Faraj al-Libbi.
Officials told Reuters news agency that the suspect became al-Qaida operations chief two years ago, and that he could provide leads to the whereabouts of top leader Osama bin Laden and his deputy Ayman al-Zawahiri.
The capture of Abu Farraj al-Libbi near the town of Mardan was announced late Wednesday, and officials say he has been taken to Rawalpindi for questioning. Pakistan accuses him of orchestrating two unsuccessful attempts to assassinate President Pervez Musharraf in December 2003.