HYDERABAD, Jan 20: The investigation into Tuesday's explosion underneath the Hyderabad bypass is said to have made headway as the investigators are about to reach the miscreants.

Reliable police sources told this correspondent on Thursday that the culprits had almost been identified but the only hurdle was collection of corroboratory and circumstantial evidence that was to be adduced to substantiate the case against them.

Following explosions on transmission and gas supply lines in Dadu last year, the then RPO, Hyderabad region, Ghulam Mohammad Malkani, had formed an investigation team, comprising Hyderabad DPO A. D. Khwaja, DPO Dadu Javed Odho and Hyderabad investigation SP Pir Fareed Jan.

The same team, in which some more officials have been inducted from Jamshoro and Hyderabad, is investigating the bypass blast.

A source said facts collected so far revealed that the same group had carried out explosions in Dadu and on railway tracks in Hyderabad. "The investigators have been monitoring the movement of the group for quite some time", the source claimed and added that group members had changed their hideouts after the bypass explosion.

However, he further said, following Tuesday's explosion, some changes had been noted by the investigators and that was why facts were being recollected and verified with a close vigil on the movement of the group.

Police officers hope that they will soon get a breakthrough provided police obtain some circumstantial evidence to bring the accused to the book formally.

The source refused to disclose identity of the miscreants involved in the incidents. He maintained that security agencies had been separately conducting investigation in the matter as well.

He said police officials had also verified records of coal mines in Dadu and Jamshoro districts to know legal or illegal sources that provided explosives to the miscreants.

Another source said two activists of a nationalist party, Fayyaz Janwari and Samiullah Kalhoro, had been picked up by police following blasts on a gas supply line and Wapda transmission lines in March, April, June and September last year as well as explosions on the Tando Adam railway track. He said they were still being grilled.

Police officials had inspected stock of explosives in coal mines, said another source. He added that coal mines' owners had informed the investigators that for over a year no blasting had taken place in the mines and now coal was only being produced. The coal mine owners said they were not getting explosives now.

He said the owners claimed to have made representations to the Sindh home department to give them permission for getting explosives from the NWFP and Punjab but the home department was quite reluctant keeping in view risks involved in transportation of explosive material from the two provinces to Sindh.

The owners do not have licences for manufacturing explosives, that is why they have to obtain it through legal or illegal outlets for blasting purposes.

Meanwhile, police patrolling has been intensified on the railway track and bypass and more pickets have been set up for surveillance of these installations.