Ending the violence in Baghdad could take a year or more, Iraq's deputy prime minister has warned.
The latest attacks have destroyed a number of buildings
Salam Zaubai said mistakes had been made in implementing the early stages of the security plan for the capital.
His comments came a week after US and Iraqi military commanders said the plan had achieved positive results.
Bodies were still being recovered from the latest attacks in the capital, in which at least 67 people died and more than 300 others were injured.
The series of rocket, mortar and bomb attacks hit eastern areas of Baghdad within a short space of time, reducing some buildings to piles of rubble.
Local people say insurgents hired rooms in order to leave bombs in them. Police say devices were placed in nine separate buildings.
'Peace still possible'
The Baghdad security plan was launched in June, in an attempt to crack down on a growing wave of violence in the city.
As part of the crackdown, extra Iraqi and coalition troops have been brought into the capital, targeting the most violent districts.
Mr Zaubai said the problems with implementing the plan were being corrected, but insurgents and sectarian militias would not be defeated quickly.
He was speaking after meeting former US Secretary of State James Baker, who was on an unannounced visit to Baghdad.
Despite Mr Zaubai's warning, his office issued a statement saying "achieving peace and security and putting an end to the violence is still possible despite the big challenges facing the government".
The health ministry said on Friday the overall death toll across Iraq for August was lower than that for July.
But the BBC's James Shaw in Baghdad says it is by no means clear the long-term trend will be downwards.