WASHINGTON — U.S. troop morale improved in Iraq last year, but soldiers fighting in Afghanistan suffered more depression as violence there worsened, according to an Army mental health report.

And in a recurring theme for a force strained by its seventh year at war, the annual battlefield study released this month found once again that soldiers on their third and fourth tours of duty had sharply greater rates of mental health problems than those on their first or second deployments.

The repositioning of troops closer to the Iraqi population last year, part of counterinsurgency tactics, made it harder for soldiers to get mental health treatment, the study found.

The report recommended longer home time between deployments, more focused suicide-prevention training and sending civilian psychologists and other mental health professionals to the warfront to add to the uniformed corps there. Officials said they've had some civilian volunteers.

The report was drawn from the work of a team of mental health experts who traveled to the wars last fall and surveyed more than 2,200 soldiers in Iraq and nearly 900 in Afghanistan. In the fifth such effort, the team also gathered information from more than 400 medical professionals, chaplains, psychiatrists, psychologists and other mental health workers serving with the troops — coming away with statistics on a range of issues such as marital problems, mental illness and troop ethics.

"They do show the effects of a long war," Col. Elspeth Ritchie, psychiatry consultant to Army Surgeon General Lt. Gen. Eric Schoomaker, said of the data.

Officials said they found rates of mental health problems such as anxiety, depression and post-combat stress were similar to those found the previous year in Iraq. That is, 27 percent of those on their third or fourth tour screened positive for a problem, compared with 12 percent of those on their first tour.

It found suicide rates "remained elevated" in both. Officials found earlier that as many as 121 Army soldiers committed suicide in 2007, an increase of about 20 percent over the year before. The preliminary figures released in January said there were 89 confirmed suicides last year and 32 deaths that were suspected suicides and still under investigation.

Soldiers in Afghanistan had rates of mental health problems similar to those in Iraq in 2007 with the exception of depression, officials said the new study showed. The percentage reporting depression in Afghanistan was higher than that in Iraq, and mental health problems in general were higher than they had previously been in Afghanistan. It said the adjusted rate last year for depression in Afghanistan was 11.4 percent, compared with 7.6 percent in Iraq.

Troops' mental health problems are linked directly to the amount of exposure they have to combat, and officials said that the level of violence last year was more pronounced in some places of Afghanistan than it was in Iraq. Some 83 percent of soldiers in Afghanistan reported being exposed to mortar fire and similar action as fighting heated up against Taliban and al-Qaida fighters, compared with 72 percent in Iraq, according to the study.