Rescuer workers Sunday morning continued to remove bodies from smoldering rubble at the luxury hotel in downtown Islamabad.
Officials said the attack had strained the capabilities of local rescue workers and the Pakistani military has been called in to help.
Militant groups in Pakistan frequently claim credit for bomb attacks soon after they occur, but no group has, as yet, come forward.
Pakistani Prime Minister Yousaf Raza Gilani made a public appeal Sunday for help in identifying those responsible.
Mr. Gilani says he appeals to the people to identify these black sheep and to isolate them because they want to destabilize the democracy and destroy the country's economy.
Officials announced a $130,000 reward for information about those behind the attack.