The number of U.S. troops killed by roadside bombs in Afghanistan soared by 60 percent last year, while the number of those wounded almost tripled, new U.S. military statistics show.

All told, 268 U.S. troops were killed by the improvised explosive devices, or IEDs, in 2010, about as many as in the three previous years combined, according to the figures, obtained by The Washington Post. More than 3,360 troops were injured, an increase of 178 percent over the year before.

Military officials said an increase in attacks was expected, given the surge in U.S. and NATO troops, as well as the intensified combat. Even so, the spike comes despite a fresh wave of war-zone countermeasures, including mine-clearance machines, fertilizer-sniffing dogs and blimps with sophisticated spy cameras.

The U.S. military has struggled for years to find an antidote to the homemade explosives — hard to detect because they lack metal and electronics. They are easily the largest single cause of casualties for U.S. troops.