KABUL, Afghanistan — American military successes in Iraq have prompted growing numbers of well-trained “foreign fighters” to join the insurgency in Afghanistan instead, the Afghan defense minister said on Tuesday.

The minister, Gen. Abdul Rahim Wardak, said at a news conference that the increased flow of insurgents from outside Afghanistan had contributed to the heightened intensity of the fighting here this year, which he described as the “worst” since the American-led forces toppled the Taliban government in 2001. American commanders have said that overall violence here has increased by 30 percent in the past year and have called for more troops.

The defense minister said that “the success of coalition forces in Iraq” had combined with developments in countries neighboring Afghanistan to cause “a major increase in the number of foreign fighters” coming to Afghanistan.

“There is no doubt that they are better equipped than before,” he said. “They are well trained, more sophisticated, and their coordination is much better.”