"Around 600 Jundullah militants are present in Karachi. They are mentally prepared and trained to commit suicide attacks," Qasim Toori and Danish alias Talha, arrested on Jan 29, were quoted as saying by a source privy to the interrogation.

Most of the suicide bombers were former students of Islamabad's Lal Masjid which was stormed by the military last July to flush out extremists, the source told the Daily Times.

The militants confessed that they had robbed foreign banks and dispatched the money to their headquarters in Wana, from where their needs for weapons, explosives and other necessities were being met.

The source added that law-enforcement personnel had also taken into custody two disabled brothers, Abu Abdullah and Gohar Muhammad, who, authorities suspect, were going to carry out suicide attacks.

The militants "confessed" that they were planning to target several key leaders of Altaf Hussein-led MQM and some high-profile government officials before the Feb 18 general elections, the Nation daily reported.

Sources told paper that the militants wanted to target top leadership of MQM and its workers as the party had supported the military crackdown on Lal Masjid.