U.S. helicopter shot down in Afghanistan

KABUL (Reuters) - A helicopter belonging to U.S.-led coalition troops was shot down by small-arms fire in Afghanistan on Wednesday and America's top military officer said he was increasingly concerned about the rising violence.

The U.S. military said there were no serious injuries when the UH-60 Blackhawk helicopter was brought down south of Afghanistan's capital.

Adm. Mike Mullen, chairman of the U.S. Joint Chiefs of Staff, told reporters in Washington the Taliban had become more effective.

"I am, and have been for some time now, deeply troubled by the increasing violence there," he said. "The Taliban and their supporters have, without question, grown more effective and more aggressive in recent weeks, and as the casualty figures clearly demonstrate."

In May, more U.S. and coalition troops were killed in Afghanistan than in Iraq for the first time since those wars began, according to the Pentagon. More than 70,000 foreign troops are now deployed in the country.

The austere Islamist Taliban have vowed to step up their campaign of guerrilla, suicide and roadside bomb attacks this year to undermine Afghan support for the government in Kabul and pressure foreign troops to pull out.

"It has been a tough month in Afghanistan, but it's also been a tough month for the Taliban," U.S. President George W. Bush said in Washington. "One reason why there have been more deaths is because our troops are taking the fight to a tough enemy."

Pilots landed the stricken Blackhawk helicopter safely and evacuated all personnel before it caught fire in the Kharwar district of Logar province, where Taliban militants are active.

It was the second coalition helicopter to crash in a week. The other incident, in the northeast Kunar province, is under investigation but indications are that the helicopter crashed due to mechanical failure, a U.S. military spokesman said.