In another incident, however, two cars parked outside a textile plant in the city of Hillah and laden with explosives blew up as workers were exiting the building, killing at least 36 people and wounding more than 140 others.

A car bomb and roadside bomb were also detonated at a market in the city of Suweira, Wasit province, killing eifght people and injuring 29 more.

Earlier, a car bomb in Tarmiya north of Baghdad targeting a police officer, killed three people and injured 16. One of the roadside bombs, set off as a patrol passed, also killed two civilians.

The rest of the deaths in Baghdad were reported to be security forces.

A suicide bomber targeting a police checkpoint also killed two people in the northern city of Mosul.

In the western city of Fallujah, four separate bombs killed four people, while 10 police officers were wounded in the western on Monday after explosives were planted outside their homes.

Rising violence

The attacks on Monday showed a new tactic being used by anti-government fighters in the country, Reuters news agency quoted an interior ministry spokesman as saying.

"This was a message to us that they can attack us in different parts ... at the same time because they have cells everywhere," he said.

The attacks come just two days after reports that the Iraqi defence ministry was considering building a "security fence"around the capital as a way of curbing violence and controlling the movements of anti-government fighters.

Access to the city would be controlled by eight checkpoints, and construction could be completed by mid-2011, reports from local broadcaster Al Iraqiya Television said.

Today's attacks undermine US confidence in Iraqi security performance [Reuters]

Violence across Iraq has dropped significantly since 2006 and 2007, when the country's sectarian conflict was at its height. But attacks have been on the rise in recent months, particular in Baghdad.

National parliamentary elections on March 7left no clear winner, and continuing wrangling by political blocs to form a governable coalition have left an atmosphere of instability in the county.

'Backlash'

Security forces have in recent weeks also made a series of arrests of high-profile members of the al-Qaeda in Iraq group, Al Jazeera's Mike Hanna, reporting from Baghdad, said.

"Certainly, authorities were predicting a backlash against that, we had seen a number of attacks recently, but this is the most serious in terms, not only of the death toll, but of the sense of co-ordination," he said.

"It would be a very strong answer, if indeed it is an al-Qaeda group [behind Monday's strikes], that despite the fact that their leadership is gone, they are still capable of carrying out this type of attack."

US withdrawal timetable

Today's attacks raise concerns over the withdrawal schedule of US troops, and whether US military commanders would review the competence of Iraqi security forces.

"There is no doubt that this type of violence could have an impact on the timetable of the US forces withdrawal timetable," Hanna said.

"The whole point of the troops being here in the first place was to guarantee security. They [US military] are expressing confidence that Iraqi security services have the competence to be able to maintain a secure country. But events like today undermine that sense of confidence and undermine that the Iraqi security forces are in fact in place to take over an efficient administration on a security basis of the country as a whole."

Police said three of checkpoints fired at on Monday were in the west of Baghdad, with two more in the east and one in the south. The checkpoints that were bombed were in the south and southeast of the capital.