The number of soldiers who took their own lives while serving in Iraq and Afghanistan rose in 2005 over the previous year, as the U.S. Army experienced its highest suicide rate since 1999, officials said on Friday.

The Army released statistics showing that 12.9 per 100,000 U.S. soldiers committed suicide in 2005, up from 11.0 per 100,000 in 2004. The 2005 suicide rate was the highest for the Army since 13.1 per 100,000 in 1999.

The Army is the largest service in the U.S. military and provides most of the troops fighting in Iraq and Afghanistan.

The Pentagon also released data showing the suicide rate in 2005 dropped from the previous year in both the Marine Corps and the Navy. Air Force data was unavailable.

Army officials discounted the notion that the increase was caused by mounting combat stress on deployed soldiers as the wars in Iraq and Afghanistan grind on. Officials said the Army rate remained lower than the rates for U.S. civilians.

Last year, 83 Army soldiers on active duty committed suicide, 25 while deployed in the Iraq and Afghanistan wars, the Army said. In 2004, 67 soldiers on active duty committed suicide, 14 while deployed for those wars, the Army said.

“We’re not alarmed,” said Col. Joseph Curtin, a senior Army spokesman at the Pentagon.

Curtin noted that last year’s total for suicides in Iraq and Afghanistan was identical to the number who killed themselves while serving in the two wars in 2003. A total of 76 U.S. soldiers committed suicide in 2003, including 25 deployed in those wars.

Curtin said the Army was not aware of any single reason for the rise last year, adding that a range of factors can include financial reasons, failed relationships, drugs and alcohol.

“In some cases it may be due to combat stress, but that’s not the bottom line. It may accentuate the reason why they commit suicide if it happens in a combat environment,” Curtin said.

The Army also said over the past two years it has increased the number of behavioral health experts deployed with soldiers in an effort to prevent suicides.

“We take suicide prevention extremely seriously and we continue to invest resources toward helping commanders in identifying and preventing soldiers who have suicidal thoughts in order to seek help right away,” Curtin said.