BAGHDAD: Foreign Minister Hoshyar Zebari said Saturday 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 on 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 on 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 re-appraisal 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."

On Saturday, dozens demonstrated against the government's plans to remove blast-proof concrete T-walls on Al-Rasheed street, the oldest thoroughfare in Baghdad, in a symbolic gesture of improved security in the capital.

"If they open up the road, we will be the first victims of explosions during Ramadan," said Adel Abu Mohammed, a 30-year-old street vendor, referring to the Muslim holiday which started on Saturday.

Three Iraqi soldiers were killed and three more wounded as the fasting month began in two separate attacks in Baghdad and in Baquba northeast of the capital, police said.

Wednesday's bombings sparked a war of words between one of the leading Shiite parties in the government and the leading Sunni insurgent group.

The Supreme Iraqi Islamic Council said the country was facing a "comprehensive war" and not only "simple bombings here and there."

It blamed the Sunni Arab minority which formed the backbone of toppled dictator Saddam Hussein's regime for the upturn in violence.

However, the rebel Islamic Army in Iraq, which includes officers of Saddam's disbanded military, laid the blame for the attacks on the Shiite-led government and US forces.