Many of the bodies recovered in Baghdad show signs of torture

They say that 540 corpses - many of them tortured or mutilated - were discovered in the city in June.

The number is still considerably lower than in 2006, when the monthly total of bodies found at times exceeded 1,000.

Nearly 30,000 extra US troops were deployed in Baghdad to curb sectarian violence between Shias and Sunnis.

Daily average

The discovery of bodies on the streets of Baghdad has been a grim feature of life in the Iraqi capital, the BBC's Mike Sergeant in the Iraqi capital says.

The total number dropped sharply between February and April, after the US military "surge" began, our correspondent says.

But the number of bodies found dumped in the city has risen sharply again in the last two months - to an average of about 20 a day in June, according to the Iraqi police.

Earlier this week, the Iraqi government said that the number of civilians killed across the country fell in June to the lowest level since the Baghdad crackdown began.

It said 1,241 civilians were killed in June - a drop of nearly 40% compared with 1,951 violent deaths in May.

The US military also claims that civilian fatalities have fallen significantly since the beginning of the year.

However, the Iraqi government figures cannot be verified independently, and many deaths are believed to go unreported, correspondents say.