BAGHDAD — Iraqi civilian deaths in Baghdad dropped significantly in June, a possible indication that recent American military operations around the country and raids on car-bomb shops in the "belts" ringing the capital are starting to pay off.

But June also marked the end of the bloodiest quarter for U.S. troops since the war began in March 2003.

Unofficial figures show 189 Iraqis, including police and government security forces, were killed in the capital through Friday, a drop of nearly two thirds since this year's high in February, when 520 were killed. The average monthly death toll of Iraqis in Baghdad was 410 from December through May.

The downturn in civilian deaths in Baghdad, should the figures hold, could arm Lt. Gen. David Petraeus, the top U.S. military commander in Iraq, with the kind of results he needs to forestall pressure to set timetables on troop withdrawals. He is scheduled to deliver a progress report on the war to Congress in September.

Securing the capital remains the U.S. military's top priority.

The trade-off for the decline in civilian deaths in Baghdad may be high U.S. casualties. The Web site icasualties.org tallied 101 U.S. soldiers killed in June, one of the deadliest months in Iraq for American forces. This raised to 330 the number of U.S. troops killed in the last three months.

The U.S. military, having added 28,500 additional forces, are now at full "surge" strength of 150,000 and are engaged in high-profile military campaigns to pacify the country.

U.S. commanders warn a higher body count is in the offing, as forces step up fighting this summer. Forty-four of the U.S. casualties in June occurred in Baghdad, caused mostly by roadside bombs — five of them Thursday in an attack involving a roadside bomb, gunfire and grenades in Baghdad's southern Rasheed district. Seven soldiers were wounded, the military said.

But the same U.S.-led surge that is taking the fight to insurgents in Iraq is apparently still placing civilians in the crossfire.

At least 22 Iraqi citizens have died, mostly outside the capital, during U.S. clashes with Sunni insurgents and Shiite militia over the past eight days, according to Iraqi police reports. The U.S. military does not disclose the numbers of Iraqi civilians killed by American troops, despite repeated requests from McClatchy.

Civilian deaths seemingly are inevitable in urban guerilla warfare that pits U.S. forces against fighters who live among the population. U.S. military officials say they are sensitive to potential backlash that could enflame anti-American opposition here.