The cell, known as the Lashkar-e-Khorasan, has been tasked to identify, capture and execute people working for what is described as a "web of local spies" created by the US Central Intelligence Agency, The Express Tribune newspaper quoted its sources as saying.

The Lashkar draws it strength from the Haqqani network and the Hafiz Gul Bahadur group ¿ two Taliban factions that control regions along the Afghan border, the report said.

The Tehrik-e-Taliban Pakistan led by Hakimullah Mehsud has its sympathies for the cell and provides occasional "active cooperation" to the Lashkar.

Though the exact number of members of the Lashkar is not known, a source in the tribal areas told the daily it was more than 300.

The regions where the cell works are Datta Khel, Miramshah, Mir Ali and surrounding areas where US drone strikes have been frequent.

The cell was set up last year by top commanders of the Haqqani network and the Hafiz Gul Bahadur group, which have a "tacit peace understanding" with Pakistan troops operating in South Waziristan.

The military operation in South Waziristan is aimed at rooting out home-grown Taliban striking inside Pakistan.

"In the beginning, it was a loose network with members casually going out and trying to find out who is providing information to the US... It is more organised now and they areworking scientifically on the counter-intelligence line," an associate of one of the groups told the daily.

An intelligence official at the Pakistan Army headquarters in Rawalpindi and local sources in Mir Ali and Miramshah too confirmed the existence and activities of the Lashkar but appeared unaware of its structure, the report said.

The US stepped up its drone campaign in the mountainous border regions last year to eliminate what US officials called high-value targets, including top leaders of Al Qaeda and their local facilitators.

The unmanned aerial vehicles operated by the CIA to eradicate Taliban militants in Pakistan's border areas struck more than 100 times last year alone.