An expert in explosives and computers, Mohammed Ali Qasim, alias Abu Sohaib al-Makki, 34, had been involved in recent terror activities in Karachi, reported Dawn Thursday.

A senior security official said that Yemeni-origin Qasim's arrest has yielded a "treasure trove" of information.

The exact date of his arrest is not known, but it is understood that he was held days after Al Qaeda chief Osama bin Laden was gunned down May 2 by US commandos who stormed his Abbottabad hideout.

Before moving to Karachi, Qasim stayed in South Waziristan, North Waziristan, Peshawar and Faisalabad.

The media report said that the Al Qaeda operative had been in Pakistan since June 2001.
Initial investigations have shown that he earlier operated along the Pakistan-Afghanistan border facilitating movements of Al Qaeda operatives.