WASHINGTON - More than 1,000 American troops have been wounded in battle over the past three months in Afghanistan, accounting for one-fourth of all those injured in combat since the U.S.-led invasion in 2001.

The dramatic increase has filled military hospitals with more amputees and other seriously injured service members and comes as October marks the deadliest month for American troops in Afghanistan.

Expanded military operations, a near-doubling of the number of troops since the beginning of the year and a Taliban offensive that has included a proliferation of roadside bombings have led to the great increase in casualties. U.S. troops in Afghanistan are suffering wounds at a higher rate than those who were serving in Iraq when violence spiraled during the military "surge" two years ago. In mid-2007, 600 American troops were wounded in Iraq each month out of the about 150,000 troops deployed there. In Afghanistan, about 68,000 troops are currently installed, with about 350 wounded each month recently.