Six U.S. troops were killed in Iraq, two of them in a helicopter crash, the U.S. military reported today, and a suicide car bombing south of Baghdad left at least 22 Iraqis dead and scores of others wounded.

Amid continuing insurgent violence, the Iraqi government appealed to former junior officers in the armed forces of ousted president Saddam Hussein to return to the military. The appeal effectively repudiates a U.S. policy imposed soon after the invasion of Iraq and ouster of Hussein, when U.S. administrator L. Paul Bremer abruptly disbanded the Iraqi military.

Two U.S. Marines were killed today when their AH-1W Super Cobra helicopter crashed near Ramadi while flying "in support of security and stabilization operations," the U.S. military said in a statement. It said the cause of the crash was under investigation.

A separate statement said a Marine and a sailor assigned to the II Marine Expeditionary Force were killed when their vehicle was hit by a roadside bomb in Ramadi on Tuesday. The two were killed "while conducting combat operations against the enemy," the statement said.

South of the capital, a U.S. soldier assigned to Task Force Baghdad was killed today by another roadside bomb, the military said.

No other details were immediately released on the incidents.

The military later reported that a U.S. soldier from the Army's 3rd Infantry Division died of wounds he sustained when his patrol was attacked today near Balad, a city about 50 miles north of Baghdad. Another soldier was wounded in the attack.

"During the fight, a gunman was quickly killed after throwing a hand grenade at the patrol, and another fled into a nearby building and continued to engage the soldiers with small-arms fire," a statement said. "U.S. Air Force aircraft were called in and dropped two bombs, killing the remaining gunman and ending the fight."

Witnesses told news agencies that the Marine helicopter had come under fire, but there was no independent confirmation of that claim. Reuters news agency quoted witnesses as saying U.S. forces quickly cordoned off the area while more helicopters buzzed overhead and that U.S. airstrikes hit the area shortly afterward.

The U.S. military said a fighter plane dropped two 500-pound bombs near the site of the helicopter crash, targeting a suspected insurgent command center. Ramadi, about 70 miles west of Baghdad, has been a center of insurgent activity by Sunni Muslims.

The new U.S. deaths came after U.S. forces in Iraq suffered one of the deadliest months of the war, with at least 93 service members reported killed in October.

The suicide bombing south of Baghdad apparently targeted a Shiite Muslim mosque in the town of Musayyib. It came on one of the last days of the Muslim holy month of Ramadan and ahead of the three-day Eid holiday, which starts later this week.

The mainly Shiite town has been rocked by several attacks, including a suicide bomber attack on a fuel truck in July that killed 98 people.

In Baghdad, Defense Minister Sadoun Dulaimi, one of the few Sunnis in the Iraqi government, invited former officers with the ranks of lieutenant, captain and major to "rejoin the new Iraqi army to serve the precious homeland," Reuters reported. He asked the officers to register at recruitment centers for medical exams and interviews.

The disbanding of Hussein's military and stoppage of payments to its members have helped fuel the insurgency, Iraqi officials say.

Although the Bush administration had approved a plan to put several hundred thousand Iraqi soldiers on the U.S. payroll to provide security, repair roads and perform other tasks after the fall of Hussein in April 2003, Bremer halted the project the following month, ordering the demobilization of the entire Iraqi military and the cancellation of pensions.

In June 2003, Bremer reversed course again, ordering temporary payments to about 370,000 conscripts and 250,000 officers. But the officers were largely kept out of the new Iraqi army that U.S. authorities attempted to rebuild from scratch.