WASHINGTON — Ninety-nine American soldiers killed themselves last year, the highest rate of suicide in the Army in 26 years of record-keeping.

Nearly a third of the soldiers who committed suicide did so while serving in Iraq or Afghanistan, according to a report released yesterday. Iraq accounted for most of those — with 27 of the suicides coming from that conflict and three from Afghanistan. Also, there were 948 attempted suicides, officials said, adding that they didn’t have a comparison for previous years.

The report said the 99 confirmed suicides among active duty soldiers compares with 87 in 2005 and is the highest number since 102 were reported in 1991, the year of the Persian Gulf War, when there were more soldiers on active duty. Investigations are still pending on two other deaths.

In a half million-person Army, last year’s suicide toll translates to a rate of 17.3 for every 100,000, the highest since the Army started counting in 1980, officials said. The rate has fluctuated over those years, with the low being 9.1 for every 100,000 in 2001.

Failed personal relationships, legal and financial problems, and the stress of their jobs were factors motivating the soldiers to commit suicide, according to the report. It also found a significant relationship between suicide attempts and the number of days deployed in Iraq, Afghanistan, or nearby countries where troops were participating in the war effort.

There was “limited evidence” to back the suspicion that repeated deployments are putting more people at risk for suicide, the report said. With the Army stretched thin by years of fighting the two wars, the Pentagon has had to extend normal tours of duty this year to 15 months from 12 and has sent some troops back to the wars several times.

Officials found no direct link between suicide and deployments or exposure to combat except in how they affect a soldier’s marriage or other close relationships, Colonel Elspeth Ritchie, psychiatry consultant to the Army surgeon general, said in a Pentagon press conference.

“Unfortunately, suicide is very often a compulsive act,” she said, and the fact that soldiers are armed can make it harder to prevent.

Preliminary numbers for the first half of 2007 indicate the number of suicides could decline across the service but increase among troops serving in the wars, officials said.

The increases for 2006 came as Army officials worked to set up a number of new programs and strengthen old ones for providing mental health care to a force strained by the longer-than-expected conflict in Iraq and the global counterterrorism war entering its sixth year.