KABUL, Afghanistan — The 30 U.S. soldiers, many of them Navy SEALs, who died Saturday in the U.S. military's single biggest loss of the Afghan war, were operating in a Taliban-controlled valley where frequent U.S.-led night raids have won the insurgents popular support, area residents said Sunday.

The raids occur "every night. We are very much miserable," said Roshanak Wardak, a doctor and a former member of the national Parliament. "They are coming to our houses at night."

Wardak runs a clinic about 3 miles from the rugged Tangi Valley where insurgents early Saturday shot down a helicopter carrying the U.S. troops, an Afghan translator and seven Afghan commandoes.

Night raids have become a significant part of the U.S. strategy aimed at weakening the insurgents and compelling their leaders to accept U.S. and Afghan government offers to hold talks on a political settlement of the decade-old war.

The Taliban have suffered heavy losses in the operations, which have soared since last year to an average of 340 per month, according to a Western intelligence official, who requested anonymity in order to discuss the issue.

There has been no apparent progress toward convening peace talks, but U.S. commanders defend the raids as effective in eliminating and capturing insurgents, and gaining intelligence that leads to other militants and arms caches.

"Eight-five percent are shots not fired, when you're talking about night raids and disruption," said the Western intelligence official. "Over 50 percent of the time they hit the target that they're after, which shows the intelligence has been accurate."

Afghan commandoes participate in all such operations, he added.

The tactic, however, has proven highly controversial with ordinary Afghans amid charges that they claim civilian lives. President Hamid Karzai has demanded that they stop.

Residents of the Tangi Valley area, in eastern Wardak Province, about 60 miles southwest of Kabul, issued similar complaints about the night raids in their vicinity, charging that they have killed civilians, disrupted their lives and fueled popular support for the Taliban.

"There are night raids every day or every other day," said a second doctor who asked not to be identified because he feared for his safety. He said he lives about 100 yards from the parched riverbed where the U.S. Chinook helicopter crashed.

"The Americans are committing barbaric acts in the area and this is the reason that the Taliban have influence," he said.

The second doctor and another area resident, Abdul Rehman Barakzai, said that as many as three civilians were killed in a U.S. raid in the vicinity on Friday night. Speaking in separate telephone interviews, each said that a tailor was among the dead.

"The Taliban are so active in the region that they forced the Americans to abandon a base here about two or three months ago because the base was under attack day and night," said Barakzai, a villager who works for an association of local tribal councils. He lives about 5 miles from Joye Zarin, the hamlet where the helicopter was downed.

A spokesman for the U.S.-led International Security Assistance Force said he could not respond to questions relating to the incident until an investigation was completed. Numerous details remained unknown, including the target of those aboard the helicopter and precisely what weapon brought it down.