American troops in Afghanistan are suffering the highest rates of mental-health problems since 2005 and morale has deteriorated, the Pentagon said Thursday in a report on stress in the armed services.

Some 70 to 80 percent of troops surveyed for the report said they had seen a buddy killed; roughly half of soldiers and 56 percent of Marines said they had killed an enemy fighter.

Two-thirds of the troops said that a roadside bomb - the No. 1 weapon of insurgents - had gone off within 55 yards of them.

Those incidents were

higher than what troops experienced in 2010 in Afghanistan, as well as during the 2007 surge of extra troops into Iraq, the report said.

The new data come from

a mental-health team that polled more than 900 soldiers, 335 Marines, and 85 mental-health workers on the Afghan battlefield last July and August.

The report said officials had boosted the mental-health staff in the country to one for every 646 troops last year, compared with one for every 1,123 in 2009.

- Associated Press