The United States has expanded its force in Iraq to 140,000 troops, the most since January and 13,000 more than five weeks ago, the Pentagon said on Thursday, amid relentless violence in Baghdad and elsewhere.

This follows July's decision by commanders to augment the U.S. military presence in Baghdad to try to curb escalating sectarian violence that has heightened concern about all-out civil war in Iraq.

As American troops continue to fight a tenacious insurgency nearly 3 1/2 years into the war, U.S. military deaths in Iraq reached at least 62 in August -- increasing from 43 in July and ending three straight monthly declines.

August's total still was about average for a war in which about 64 U.S. troops have died per month. There have been 2,635 U.S. military deaths since war began in March 2003, and another 19,773 troops have been wounded in action, the Pentagon said.