"We got to know about the bomb on Friday night when an anonymous phone caller warned us that it was planted in a car parked outside the Park Tower," Senior Superintendent Police Azad Khan told Deutsche Presse-Agentur.
"The bomb contained 10 kilogrammes of RDX explosive material, connected with a remote controlled detonator," he said.
The launching ceremony of Harry Potter and the Deathly Hallows due to be held on early Saturday in the Park Towers was postponed.
"We are not sure so far whether the target of the bombing was the book launch, but the connection cannot be ruled out," Khan said.
The police was looking for the caller who informed them of the planned terrorist attack.
"It could as well be some character of the Harry Potter series," Khan joked.
Deutsche Presse Agentur