The eight men owing allegiance to al-Qaeda used eight Russian made anti-tank shells "to create an unusual law and order situation" in order to create chaos and insecurity in the twin cities of Islamabad and Rawalpindi, Interior Minister Aftab Ahmad Khan Sherpao told reporters in Islamabad.

Without directly saying if they tried to target Musharraf, who himself had acknowledged two days ago that it was yet another bid on him by al-Qaeda, Sherpao said the militants first deployed eight shells in three different places, four in Ayub Park close to Musharraf's residence and two each near the Parliament and the greens close to ISI headquarters.

"These anti-tank shells were deployed by the miscreants/ terrorists in one go in all the three places. These shells had to take off and hit their target simultaneously through mobile set signals," he said.

"Fortunately, none of these devices took off but one such shell could take-off and hit the area of Golf course on the night of October 4," he said, adding that the rest of the shells placed near the Parliament and ISI headquarters were recovered the next day in "sweep" operations by the security forces.

Declining to identify the Pakistani militant group or the individuals arrested, he said "investigations are under progress and indications are that they are linked with al-Qaeda."

Earlier reports said an army deserter was among those arrested in connection with the October 4 blast near Musharraf's residence as also the recoverey of four anti-tank shells.

Sherpao said the breakthrough in the case came after the mobile phone sets attached to the shells were "decoded" and the contact numbers of the "culprits" were obtained and the owners traced. "The culprits were therefore identified and were rounded up for the through investigations.

A cache of explosive materials and ammunition has also been recovered," the minister said. More arrests and recoveries of explosives were expected in the next few days, he said. Talking to reporters at a get-together on Wednesday, Musharraf had said it was a crude attempt to assassinate him and its perpetrators have possible links to Osama bin Laden's al-Qaeda terror network.

"I am not an easy target. We have unearthed the whole gang, caught the culprits who are extremists," he said. "The perpetrators were all religious extremists, perhaps linked to a group having contacts with al Qaeda, but they were not fully trained in carrying out such a task," said the general, who survived two attempts on his life in 2003 by al-Qaeda militants.