Bombers and gunmen launched an apparently coordinated string of attacks against Iraqi government forces on Wednesday, killing at least 46 people a day after the number of U.S. troops fell below 50,000 for the first time since the start of the war.

The violence highlighted persistent fears about the ability of Iraqi troops to protect their own country as the American military starts to leave.

There were no claims of responsibility for the spate of attacks. But their scale and reach, from one end of the country to the other, underscored insurgent efforts to prove their might against security forces and political leaders who are charged with the day-to-day running and stability of Iraq.

The deadliest attack came in Kut, 100 miles (160 kilometers) southeast of Baghdad, where a suicide bomber blew up a car inside a security barrier between a police station and the provincial government's headquarters. Police and hospital officials said 16 people were killed, all but one of them policemen. An estimated 90 people were wounded.

Government employee Yahya al-Shimari, 40, was headed to work when the blast hit.

"I rushed to the scene to help evacuate the people, and saw body parts and hands scattered on the ground and dead bodies of policemen," al-Shimari said. "I also saw a traffic policeman lying dead on the ground. There were about 15 cars that were burnt."

An eerily similar attack came in a north Baghdad neighborhood, where a suicide bomber detonated a car bomb in a parking lot behind a police station.

Fifteen people were killed in that attack, including six policemen. Police and hospital officials said another 58 were wounded in the explosion that left a crater three yards (meters) wide and trapped people beneath the rubble of felled houses nearby.

Four others, including an Iraqi soldier and a police officer, were killed in small bursts of violence in Baghdad.

A senior Iraqi intelligence official raised the possibility that some of the attackers had inside help. The official, who spoke on condition of anonymity because he was not authorized to talk to the media, said the Baghdad suicide bombing bore the hallmarks of al-Qaida, but said unnamed political factions helped coordinate some of the other attacks. He refused to elaborate.

Since Iraq's March 7 elections failed to produce a clear winner, U.S. officials have feared that competing political factions could stir up widespread violence. Iraqi leaders so far have tried to end the political impasse peacefully.

But U.S. and Iraqi officials alike acknowledge growing frustration throughout the nation, nearly six months after the vote, and say that politically motivated violence could undo security gains made over the past few years.

"What is going on in the country?" said Abu Mohammed, an eyewitness to a car bombing near Baghdad's Adan Square that killed two passers-by. "Where is the protection, where are the security troops?"

Still, some security forces proved to be on guard. Police in the northern city of Mosul said Iraqi soldiers shot and killed a suicide bomber Wednesday afternoon as he sought to blow up his car outside an army base.

From the northern Iraqi city of Kirkuk to the holy Shiite shrine town of Karbala, scattered bombings killed and wounded scores more. They included:

_A local council building in Muqdadiyah, north of the capital, was hit with a car bomb. Three people were killed and 18 wounded, said Diyala police spokesman Maj. Ghalib al-Karkhi.

_In the former insurgent stronghold of Fallujah, police said a soldier was killed and 10 people wounded when a suicide bomber rammed his car into an Iraqi army convoy.

_Car bombs in Kirkuk, Iskandariyah, Dujail and Mosul killed six and wounded 29. A roadside bomb in Tikrit, Saddam Hussein's hometown, killed a policeman on patrol and wounded another.

_A car bomb near police station in Karbala wounded 28 people but no fatalities were immediately reported. Two people in the southern port city of Basra were also injured by a car bomb.

While violence has subsided significantly since the height of the sectarian bloodshed in 2006 and 2007, militants continue to target members of Iraq's nascent security forces, undermining their ability to defend the country as the U.S. ends combat operations.