“Experts are examining the few remains of the bomber's body in a bid to identify him,” said the interior ministry crisis management chief Brig Javed Cheema.
Officials said a sketch of the bomber could not be prepared as no witnesses had so far come forward, nor had hotel security cameras filmed the attacker.
Interior ministry officials said no group had yet claimed responsibility for the attack.
“We suspect (the attack) could be by militants opposed to the government's drive against Taliban elements in the tribal regions,” a senior security official said.
The official said the bomber appeared to be ill-trained and poorly briefed, which suggested he was from the northwestern tribal belt rather than affiliated to better-funded sectarian groups.
“The door where he tried to enter is locked from inside and there is security present in front of it. Even if the guard had not stopped him, it would not have been possible for the bomber to enter the premises,” the official said.
The pattern of the bombing closely resembled suicide bombings in Afghanistan, where scores of such attacks last year blamed on the Taliban did not cause widespread damage and killed mostly the bombers, he added.
President Pervez Musharraf condemned the suicide attack and said it would not affect the “unwavering commitment” of the government to root out terrorism and extremism from the country.—AFP