WASHINGTON — Heavier guns and sturdier trucks would not have saved a team of Blackwater USA guards brutally killed in March 2004 after being lured by corrupt Iraqi forces into a well-planned ambush, the embattled private security contractor contends in a report to Congress.

This conclusion sharply contradicts the findings of a congressional investigation led by House Democrats and a wrongful-death lawsuit filed by the families of the four slain guards, including Big Island native Wesley Batalona.

Blackwater is cast in both as an incompetent, penny-pinching outfit that sent an undermanned and poorly equipped detail through Fallujah, a known insurgent stronghold 40 miles west of Baghdad.

In the 10-page report, obtained by The Associated Press and delivered yesterday to lawmakers, Blackwater says Democrats and the lawyer for the families have teamed up against the company for political gain.

While calling the deaths "a tragic event," Blackwater says the incident was unavoidable and the guards — former Navy SEALs and Army Rangers — understood the risks of their mission and could have refused to go.

"Stronger weapons, armored vehicles, ammunition or maps would not have shielded these brave military veterans from the certain death that awaited them on that morning," Blackwater says. "Even if Blackwater had placed six men on the mission, the result would likely have been the same."

Members of the Iraqi Civil Defense Corps, swayed by sectarian influences, "intentionally betrayed" the Blackwater guards, the report says — a deception no amount of equipment, training or skill could overcome.

"It was ICDC betrayal and enemy ambush — not contractor incompetence — that led to the deaths of four Blackwater personnel on March 31, 2004," the company says.

In a Sept. 27 report on the Fallujah incident, the Democratic staff of the House Oversight and Government Reform Committee agreed the guards were ambushed by insurgents but said there was no evidence the civil defense corps participated.

The Democratic staff report said Blackwater cut two guards from the Fallujah mission, leaving the team without rear gunners.

The Mitsubishi Pajeros that Batalona, Jerry Zovko, Michael Teague and Scott Helvenston were driving had armor plates behind the back seats but were otherwise just sport utility vehicles, the staff said.

According to Blackwater, a civil defense corps representative showed the guards the fastest route through Fallujah. Upon approaching downtown Fallujah as directed, the convoy of three supply trucks and two Blackwater vehicles was stopped briefly at a busy intersection by Iraqi police.

As the convoy moved out of the intersection, at least five assailants opened fire at close range with AK-47s. Two of the attackers held weapons in one hand and video cameras in the other, the company says.

"The fact that the assailants were set to record the murders is further proof that there was a pre-existing plan at work," according to Blackwater.

Escape routes were cut off by oncoming traffic. The truck drivers — all third-country nationals — escaped unharmed.

"The ambush, apparently, was only intended to kill the Americans," Blackwater's report says.

Travel in Iraq in unarmored vehicles was common, the company's report says, and Blackwater was not contractually bound to use armored carriers. Even if it had been, "concentrated, proximate AK-47 fire can effectively penetrate" the windows of armored vehicles, the report says.

Blackwater's current contract with the State Department expires in May, but the fallout from a September shooting in Baghdad puts its future work in Iraq in jeopardy. But Blackwater won't be going quietly. The company accuses the Democratic staff of ignoring key facts about the Fallujah killings in an effort to "cast blame for the murders."

Daniel Callahan, the attorney for the families, is blamed for urging a partisan probe of Blackwater.

The families of the slain contractors filed suit against the company in January 2005, saying Blackwater's cost-cutting measures led to the deaths.

The company's report cites a Dec. 13 letter to House Speaker Nancy Pelosi, D-Calif., in which Callahan requested that Congress aggressively investigate Blackwater. He told Pelosi that the security contractor is an "extremely Republican" company that put safety behind its quest for war profits.

"That's ridiculous," Callahan said yesterday of any political motivations behind the lawsuit.

Erik Prince, Blackwater's top executive, has contributed heavily to Republican causes and has hired former Bush administration officials to work for Blackwater.

The State Department yesterday ordered additional revisions to the way it regulates its security contractors abroad after an expert panel issued a blistering report suggesting the current system was flawed and dangerous.

Recommendations from the four-member panel include cultural sensitivity training for contractors and an effort by the State Department to increase the number of Arabic-speaking contractors in Middle Eastern countries.

The Los Angeles Times contributed to this report.