The number of attacks in Iraq has dropped to its lowest levels since the months following the 2003 U.S.-led invasion, a security improvement that comes as the U.S. begins downsizing its operation, a U.S. military spokesman said Wednesday.

Maj. Gen. David Perkins also said the number of American troops, Iraqi security forces and civilians killed also have dropped dramatically since the height of violence.

"At the height of the violence, we were averaging 1,250 attacks a week," Perkins told reporters in Baghdad during a news conference. "Now, many times, we have less than 100 a week."

President Barack Obama has announced the withdrawal of American combat troops from Iraq by the end of August 2010, leaving up to 50,000 U.S. soldiers to train Iraqi forces. Under an Iraqi-U.S. security agreement, all U.S. troops are to leave Iraq by 2012.

Currently there are more than 135,000 U.S. troops in Iraq, and their withdrawal will be gradual at first to leave most in place for parliamentary elections at the end of this year. About 12,000 troops, which make up two of 14 combat brigades in Iraq, are scheduled to leave by September. They will not be replaced.

Perkins said that in January and February of last year, 148 U.S. troops were killed in Iraq. In the first two months of this year, 19 troops died due to hostile fire.

"If you take a look at military deaths, which is an indicator of violence and lethality out there, U.S. combat deaths are at their lowest levels since the war began six years ago," Perkins said.

At the height of violence in Iraq, two million Iraqi civilians fled their homes amid sectarian violence that saw thousands killed. The strife prompted the U.S. to send an additional 30,000 troops to Iraq.

Perkins said since the peak of the U.S. troop surge that saw 165,000 personnel in Iraq in 2007, attacks against civilians have decreased by 90 percent.

"For instance, in the last two weeks, we have had no ethno-sectarian attacks reported in Iraq. And many times those are the most deadly and they tend to lead to a spiraling out of control of violence," he said. "So it is very good news."

Perkins credited the security gains to improvements made by Iraqi security forces and the diminishing insurgent threat posed by al-Qaida in Iraq and other extremist groups.

Perkins said joint U.S.-Iraqi military operations in recent months have targeted everything from insurgent funding to recruiting, making a significant impact in their ability to plan and carry out attacks.

Maj. Gen. Qassim al-Mousawi, an Iraqi military spokesman, told reporters that security forces arrested three insurgents involved in a March 10 suicide attack in Abu Ghraib that killed 33 people.

Al-Mousawi did not provide further details about the arrest.

"Yes these pockets are still active but they are not affecting our morals," al-Mousawi said. "The war is still going on with the terrorism and has not come to end."