BAGHDAD — Insurgents launched a deadly coordinated attack on an American combat patrol, detonating a roadside bomb, then firing guns and rocket-propelled grenades at the soldiers, the U.S. military said today. Five troops were killed.

Seven soldiers were wounded in the attack on Thursday in southern Baghdad and were evacuated to a military hospital; one has since returned to duty, the military said.

The deaths brought to 99 the number of U.S. troops to die in Iraq this month. The toll for the past three months — 329 — made it the deadliest quarter for U.S. troops in Iraq since the war began in March 2003.

At least 3,576 members of the U.S. military have died since then, according to AP figures. The number includes seven military civilians. At least 2,936 died as a result of hostile action, according to the military's numbers.

Meanwhile, radical cleric Muqtada al-Sadr postponed a Shiite march to a bombed shrine north of Baghdad that was scheduled for July 5, an aide said.

"Muqtada al-Sadr has decided to postpone the march to Samarra for several reasons, including the government's inability to secure the route and many officials' appeals for a postponement," said Sheik Asad Al-Nassiri, an aide to the cleric. He made the announcement during a sermon today in nearby Kufa.

Sunni organizations and government officials had urged al-Sadr to cancel the march to the Askariya shrine in Samarra, which was bombed for a second time earlier this month, fearing it would escalate sectarian violence that already has claimed thousands of lives.

Al-Sadr had said the march was aimed at bringing Shiites and Sunnis closer together and breaking down the barriers imposed by the Americans and Sunni religious extremists.

Also today, the British military issued a statement saying both of its two main bases came under attack from mortars or rockets in the past 24 hours, but there were no casualties or damage.

Britain maintains a force of about 5,500 troops based mainly on the fringes of Basra, Iraq's second-largest city, 340 miles southeast of Baghdad.

In other violence, Iraqi police said at least six Iraqi soldiers were killed and five wounded when a suicide truck bomb exploded at their army post north of Baghdad.