ISLAMABAD, June 27 The US Federal Bureau of Investigation has informed Pakistan that an Al Qaeda-linked outfit, called 'Al Kini group', is behind a series of terrorist attacks in the country, including last year's suicide attack on Islamabad's Marriott hotel.

It has also asked the Federal Investigating Agency to share its findings gathered through interrogation of the arrested suspects to help hunt down the top members of the group.

In its latest communication to the FIA, the FBI said the Al Kini group was not only involved in the Marriott bombing, but its various terror cells were also involved in the suicide attack that killed the Army's surgeon general, Lt-Gen Mushtaq Baig, in Rawalpindi and a bomb attack on a police station in Sargodha.

Usama Al Kini, also known as Azmarai, was the Al Qaeda chief for Pakistan until he was killed in a drone attack in North Waziristan last year.

It's not clear who heads the Al Qaeda network in Pakistan now, but FBI's correspondence suggests terror cells of those loyal to Al Kini are still operating as a separate group and carrying out attacks in Pakistan.

Perhaps the deadliest of the known attacks by the group was the dumper-truck bomb that caused havoc at Islamabad's Marriott in September last year, killing 53 people and injuring dozens of others.

According to the FBI, three US nationals were among those killed in the attack.

A highly informed source said the FBI had asked the FIA and Islamabad Capital Territory police to share their investigations they had carried out so far which may help them in catching three people described as absconders, including a person identified as Ibraruddin Syed.

A joint investigation team, headed by former FIA director-general Tariq Pervez, had carried out investigation into the Marriott bombing and compiled a report.

Dr Mohammad Usman, a resident of Hayatabad Peshawar, Rana Illyas Ahmed, a resident of Sumanderi (Faisalabad) and Hameed Afzal, a resident of Toba Tek Singh, were arrested by the Pakistani security agencies for alleged involvement in Marriott bombing and they are being tried in the ATC.

The source said in line with the FBI's request, the FIA director-general had sought permission from the federal government to share their findings with the US agency for detaining individuals involved in the bombing as three Americans had been killed in the terrorist attack on the hotel.

The FBI also asked the FIA to have a meeting with the team that had investigated the Marriott bombing and initiate joint efforts to bring the culprits to book.

The FIA has also been requested to allow the FBI to carry out some forensic tests in their laboratories on leftover pieces of the explosive-laden vehicle, frame parts, engine and its shrapnel which were seized by the Pakistani agencies.

The FBI believes that the relevant forensic testing on residue samples, found from the scene of the terrorist attack, would help the Pakistani authorities in their investigation.

The source said information collected from one of the arrested members of Al Kini group, Omar Farouk, revealed that the group had financed two terrorist attacks in Pakistan in 2007, including an attack on the Sarghoda police station in 2007.

It seems the FBI has stepped up its efforts to collect further information in close liaison with the FIA and other security agencies in Pakistan to tighten the noose around Al Kini network, which many believe to be the most effective Al Qaeda wing within Pakistan.