BAGHDAD: Iraq on Sunday showed a video of a Saddam Hussein loyalist confessing to orchestrating one of two massive truck bombings that killed 95 people and maimed hundreds more in Baghdad four days ago.

Former police chief Wissam Ali Kadhem Ibrahim admitted to plotting Wednesday's attack at the finance ministry, the first of two deadly blasts on the worst day of violence seen in Iraq for 18 months.

"I received a call a month ago from my boss in the (Baath) party Sattam Farhan in Syria to do an operation to destabilise the regime," Ibrahim said in the footage, alluding to Saddam's now outlawed political movement.

The 57-year-old suspect said the truck bomb was prepared in Khalis, 80 kilometres (50 miles) northeast of Baghdad, and that he had called a contact in the nearby town of Muqdadiyah to ensure its safe passage to the capital.

Ibrahim, who said he was chief of police in Diyala until 1995 under Saddam's rule, said he had worked as a lawyer until 2002 but then became a leading Baathist official in the restive province northeast of Baghdad.

Major-General Qassim Atta, spokesman for the Iraqi Army's Baghdad operations, told reporters that Ibrahim was the main person responsible for the attack at the ministry of finance.

The second truck bombing on Wednesday occurred just minutes later at the ministry of foreign affairs.

Government officials meanwhile told AFP that they had halted the dismantling of blast-proof concrete security walls in Baghdad following last week's devastating attacks.

The decision is a step back from Prime Minister Nuri al-Maliki's plan to remove the walls to show that Iraq's security situation was improving.

The decision to stop dismantling the so-called T-walls was taken shortly after the truck bombings, high-ranking officials from the defence and interior ministries said on condition of anonymity.

The sources did not say whether some of the barriers that have already been taken down would be re-erected in the wake of Wednesday's attacks, the deadliest since US forces pulled out of urban centres at the end of June.

The walls are T-shaped concrete barriers about three metres (10 feet) high and linked with heavy-duty metal cables to protect against explosives.

On Sunday, foreign ministry staff were seen erecting a new line of T-walls and the nearby streets remained closed to traffic.

"We will re-examine our strategy on security matters," Baghdad governor Salah Abdul Razzaq told AFP during a visit near the ministry.

"It is possible we will close certain places to ensure security," he said, adding that the bombers had exploited the Iraqi people's desire to see the concrete barriers removed, ultimately making it easier to conduct the attacks.

Premier Maliki said on Saturday that Iraq had taken "decisive measures to tackle the weak points" exposed by Wednesday's bombings.

On Thursday, he ordered the arrest of 11 senior security officers so that they could be questioned on how a four-tonne truck had entered an area where even two-tonne vehicles are barred.

Foreign Minister Hoshyar Zebari two days later went further, saying Iraq would witness more deadly attacks in the coming months because security forces are colluding with insurgents and the violence is getting worse.

He also made the first official admission that the blasts signalled security gains made in the past year have recently appeared to unravel, and called for a re-appraisal of the country's entire security apparatus, saying it was not obtaining sufficient intelligence to counter the insurgent threat.