BAGHDAD--Violence dropped dramatically in Iraq in 2009 but improvements in security appear to have levelled off and insurgents have shifted tactics to larger-scale bombings, a monitoring group said on Friday.

The toll published by Iraq Body Count, which tracks the number of civilians killed as a result of violence, is markedly higher than that of the Iraqi government. However, it notes that the number of people killed in 2009 was the lowest annual total since the US-led invasion to oust Saddam Hussein in 2003.

Overall, 4,497 civilians were killed as a result of violence until December 16, less than half of 2008's total of 9,226, according to the British-based group.

The government toll, according to an Agence France-Presse tally of official monthly figures, put deaths at only 2,494 civilians killed in the first 11 months of the year, less than half the 5,886 in all of 2008.

This year "has seen a number of significant improvements in levels of armed and non-state terrorist violence in Iraq," the non-governmental organization said.

"However, even taking into account worsening conditions elsewhere in the world, such violence still afflicts Iraq's population more than any other."

And the second half of 2009 saw around the same number of civilian deaths as the first, which IBC said "may indicate that the situation is no longer improving."

Prime Minister Nuri al-Maliki has promoted himself as having improved security across Iraq, and is aiming to retain his post in parliamentary elections due on March 7.

But National Security Advisor Safa Hussein warned in an interview with AFP earlier this week that Al-Qaeda is a threat in the run-up to the vote.

"Their intention continues in this direction," he said when asked if he expected further waves of massive coordinated bombings. "I think during the election period, it will continue this way."

IBC added that "large-scale bombings ... have increased in their severity of impact," noting that 750 people were killed in eight major attacks last year.

Baghdad in particular was struck by three major coordinated vehicle bombings in August, October and December that killed around 400 people, attacks blamed on Al-Qaeda working with diehard elements of Saddam's Baath party.

The IBC report also said the restive northern city of Mosul has become more violent than the capital on a per capita basis, with 735 recorded civilian deaths in 2009 out of an estimated population of 1.8 million people.

Baghdad, which has a population of around 6.5 million people, saw 1,488 deaths.

The group added that Mosul experienced nearly twice as many violent incidents as Baghdad.

According to IBC, an emerging trend in terms of types of violence in 2009 was the increasingly prevalent use of magnetic "sticky bombs" secretly affixed to cars: the number of people killed as a result of such attacks rose to 174 in 2009 from 46 in 2008.