It was Iraq's bloodiest day in nearly a month, and the scale of the coordinated explosions in more than a dozen cities showed an apparent determination by insurgents to prove that the government cannot keep the country safe ahead of the summit.

Iraq is due to host the meeting for the first time in 20years and the government is anxious to show it can maintain security following the withdrawal of US troops in December.

"The goal of today's attacks was to present a negative image of the security situation in Iraq," government spokesman Alial-Dabbagh told.

"Security efforts will be escalated to counteract terrorist groups' attacks and to fill loopholes used by them to infiltrate security, whether in Baghdad or other provinces."

Tuesday's deadliest incident occurred in the southern city of Kerbala, where twin explosions killed 13 people and wounded 48 during the morning rush hour, according to Jamal Mahdi, a Kerbala health department spokesman.

Blasts also struck in the capital, in Baiji, Baquba, Daquq,Dibis, Dhuluiya, Kirkuk, Mosul, Samarra, Tuz Khurmato, Khalisand Dujail to the north, in Falluja and Ramadi to the west, and Hilla, Latifiya, Mahmudiya and Mussayab to the south.

Police defused bombs in Baquba, Falluja and Mosul.

Most of the blasts targeted police checkpoints and patrols.

"This latest spate of attacks is very likely to have been co-ordinated by a large and well-organised group. It is likely an attempt to show the authorities that their security measures are insignificant," said John Drake, a senior risk consultant at AKE Group, which studies security in Iraq for corporate clients.

Army and police forces are frequently targeted in Iraq, where bombings and shootings still occur almost daily.

Tuesday's attacks were the biggest since Feb. 23 when dozens of explosions across the country killed at least 60 people.