ISLAMABAD, Pakistan (CNN) -- British Airways is suspending flights to and from Pakistan indefinitely following the deadly bomb attack on the Marriott Hotel, the airline says.
The hotel was destroyed by the 600 kg bomb.
BA said it operated at least three flights a week from London's Heathrow to the Pakistan's capital Islamabad, the site of the attack.
Soon after Saturday's attack, the airline temporarily halted its flights and said it would review operations later in the week. Tuesday's announcement extends the suspension.
The suicide bombing of Islamabad's best-known hotel killed more than 50 people, including two U.S. military personnel and the Czech Ambassador to Pakistan.
The Pentagon on Tuesday named the second of the two Americans killed as Navy Petty Officer Matthew J. O'Bryant, 22, of Duluth, Georgia.
A U.S. State Department contractor is unaccounted for in the aftermath of the blast.
The bombing wounded more than 250 and sparked a fire that left the hotel in ruins.
Pakistan's president, prime minister and other leaders also had a lucky escape when plans to dine at the hotel on the night of the bombing were changed at the last minute.
President Asif Ali Zardari asked to move the event to the prime minister's compound, said Rehman Malik, the head of Pakistan's Interior Ministry.
His announcement raised questions as to how much the government knew about the planned attack, which involved a construction truck with more than 600 kg (1,300 pounds) of explosives. Watch the damage caused and hear stories from survivors »
But the hotel's owner denied the government had made reservations for that night and Pakistani Senator Javed Ashraf Qazi said he was invited to the dinner but it was always scheduled to be at the prime minister's office.
Meanwhile, Al-Arabiya TV reported Monday that it received a claim of responsibility for the attack by a previously unknown group called "The Fedayeen of Islam," but noted that it could not authenticate the audio recording or the name of the group.
According to the recording, the group said 250 U.S. Marines and other U.S. and NATO officials were inside the hotel at the time of the attack.
It said the group regretted the attack, but said it was necessary to press its demands, including an end to U.S.-Pakistani joint efforts and a halt to all military operations in Pakistan's tribal regions. Watch the damage caused and hear stories from survivors »
No arrests have been made in connection with the attack. But Malik said suspicion was falling on militants in Pakistan's tribal regions.
"I am not in a position to tell you who has done it, but (in) all the previous investigations, all the roads have gone to South Waziristan," he said.
Saturday's massive blast left a nearly 18-meter-wide (60 foot) crater, which was 7m deep (24 feet). It also caused a natural gas leak that set the top floor of the five-story, 258-room hotel on fire, police said. The blaze quickly engulfed the entire structure. At least 57 people were killed.
The blast occurred about 7:50 p.m., after the breaking of the fast during the holy month of Ramadan.
Pakistani authorities released security video of the blast, showing a small explosion inside the truck before the larger, deadly explosion.
In the video, a large truck crashes into the security gate, sending one security officer scurrying for safety. Then, as security guards approach the truck, the top of the vehicle explodes and the security guards flee. Watch guards scatter after an explosion »
A small cloud of smoke appears above the truck, which is engulfed in flames minutes later. One of the security guards tries to put out the fire with a hand-held extinguisher, to no avail. The guards then walk away, and the camera freezes on the burning truck. Watch the truck bomb caught on tape »
The Marriott, a Western brand-name hotel, has been the site of attacks in the past.