Foreign Minister Hoshyar Zebari said yesterday that Iraq will witness more deadly attacks in coming months because security is deteriorating due to collusion between security forces and insurgents.

Zebari, whose office lost 32 staff in two massive truck bombings that also targeted the finance ministry last Wednesday, admitted the latest unrest was a serious security setback and the government had failed to protect its citizens.

Wednesday's bombings came only minutes apart and killed at least 95 people and wounded about 600, marking the worst day of violence seen in the conflict-hit country in 18 months.

"How could this truck pass unless there is collaboration?" Zebari told reporters in Baghdad.

"There was collaboration between security forces and the terrorist group to facilitate the passing of this truck through such a sensitive area."

Zebari said Iraqi Prime Minister Nuri al-Maliki had ordered the arrest of 11 senior security officers last Thursday so they could be questioned on how a four-tonne truck had entered an area where even two-tonne vehicles are barred.

"These people should be held accountable if there is such a penetration," Zebari said.

He also made the first official admission that the blasts signalled that security gains made in the past year have recently appeared to unravel, a fact witnessed by a series of murderous blasts across the country.

"This has been going on for the last two months. Every week, every two weeks we see a wave of these bombings and killings of innocent people," Zebari said.

"Enough of these over-optimistic remarks about security. There has been a deterioration in the security situation, this is a fact and the coming (violence) will be bigger," he said.

Premier Maliki said after Wednesday's bombings that the attacks were "a desperate attempt to derail the political process and affect the parliamentary elections," planned for January.

But Zebari went further and called for a reappraisal of the country's entire security apparatus as it was not, he said, obtaining sufficient intelligence to counter the insurgent threat.

"They have been moving their attacks... now they have focused on their main concern, their main attention - Baghdad. This is a dangerous and a serious development and a security setback.

"The government has to reconsider the composition of its security institutions. If they are penetrated, at least at some level, then we have a serious problem," he said.

"Sometimes you can't fight these people with checkpoints. You should be mobile. You should go after them, you disrupt and penetrate their network to get human information. This is the key."