TIKRIT, Iraq (Reuters) - U.S. soldiers killed 46 Iraqis and captured eight trying to carry out a series of attempted ambushes on U.S. convoys in the central Iraqi city of Samarra on Sunday, a U.S. military spokesman said.

"The fourth infantry division repelled multiple ambush attacks," Lieutenant Colonel William MacDonald told reporters.

At least 18 attackers, five U.S. soldiers and a civilian traveling with the troops were wounded during the ambushes.

"The attacks were coordinated in locations very close to each other," he said, adding that the ambushes were made on separate U.S. convoys using mortars, grenades and small arms fire. Three buildings, from whose roofs the attackers fired, were destroyed.

"The attackers attempted to block one of the convoy’s way with a makeshift barricade," MacDonald said, citing three main attack points around Samarra, north of Baghdad.

"In all of the clashes coalition firepower overwhelmed the attackers resulting in significant enemy losses," he said. "If you attempt to attack one of our convoys we’re going to use our firepower to stop that attack."

Some of the attackers wore the attire of Fedayeen, a militia formed by Iraqi President Saddam Hussein before U.S.-led forces toppled him earlier this year.

The Fedayeen are among the former Saddam loyalists blamed by Washington for coordinating a rising insurgency against Iraq’s U.S. occupiers.

"This is the largest (ambush) for our task force since we’ve been in the area," MacDonald said.

He declined to say whether the coordinated ambushes were linked to attacks on civilian foreign nationals in the Tikrit- Samarra area in the last two days.

Samarra and Tikrit, where the 4th infantry division is based, are located in the center of Iraq where most attacks on foreign forces and Iraqis cooperating with them have been concentrated.