BAGHDAD -- Religious vigilantes have killed at least 40 women this year in the southern Iraqi city of Basra because of how they dressed, their mutilated bodies found with notes warning against "violating Islamic teachings," the police chief said Sunday.

Maj. Gen. Jalil Khalaf blamed sectarian groups that he said were trying to impose a strict interpretation of Islam. They dispatch patrols of motorbikes or unlicensed cars with tinted windows to accost women not wearing traditional dress and head scarves, he added.

"The women of Basra are being horrifically murdered and then dumped in the garbage with notes saying they were killed for un-Islamic behavior," Khalaf said. He said men with Western clothes or haircuts are also attacked in Basra, an oil-rich city some 30 miles from the Iranian border and 340 miles southeast of Baghdad.

"Those who are behind these atrocities are organized gangs who work under cover of religion, pretending to spread the instructions of Islam, but they are far from this religion," Khalaf said.

Throughout Iraq, many women wear a headscarf and others wear a full face veil, although secular women are often unveiled. Since the overthrow of Saddam Hussein and the rise of a Shiite-dominated government, men in some parts of the country have sometimes forced women to cover their heads or face punishment. In some areas of the heavily Shiite south, even Christian women have been forced to wear headscarves.

Before the U.S.-led invasion in 2003, Basra, Iraq's second-largest city, was known for its mixed population and night life. Now, in some areas, red graffiti threatens any woman who wears makeup and appears with her hair uncovered.

Khalaf said bodies have been found in garbage dumps with bullet holes, decapitated or otherwise mutilated with a sheet of paper nearby saying, "she was killed for adultery," or "she was killed for violating Islamic teachings." In September, the headless bodies of a woman and her 6-year-old son were among those found, he said. A total of 40 deaths were reported this year.

"We believe the number of murdered women is much higher, as cases go unreported by their families who fear reprisal from extremists," he said.

Harith al-Ithari, who works in the Basra offices of the Shiite cleric Muqtada al-Sadr, said the conservative religious movement opposed the killings and blamed "gangs with foreign support to destabilize the city."

"There is a concrete religious principle that says that wearing makeup and forgoing the hijab (headscarf) in public is a sin," al-Ithari said. "But killing them is a sin bigger than this one."