The government's use of murderers as informants constitutes "one of the greatest failures in the history of federal law enforcement," according to a draft report from a congressional committee.

The scathing report from the House Government Reform Committee says the Justice Department's failure to rein in criminal informants has compromised investigations nationwide with "disastrous consequences."

"Democracy succeeds in the United States when the rule of law is respected. When the government strays from the rule of law, the harm outweighs the benefit. In Boston, this is what happened," concludes the report obtained Monday night by The Associated Press.

FBI spokeswoman Gail Marcinkiewicz declined to comment, saying the agency had not seen the report.

The committee, under Rep. Dan Burton, R-Indiana, has been investigating for two years the Justice Department's use of criminal informants. It has focused on the relationship between Boston FBI agents and the hit men and mob leaders they cultivated and sometimes protected from prosecution for crimes as serious as murder.

Retired FBI agent John Connolly was convicted last year for tipping off informants about to be charged in criminal cases. One of those tipped, James "Whitey" Bulger, is still on the FBI's 10 Most Wanted list.

Last month, the House committee subpoenaed University of Massachusetts President William M. Bulger to testify about his fugitive mobster brother. But he invoked his Fifth Amendment right against self-incrimination and refused to answer questions.

According to the committee's draft report, the root of the problem with the Justice Department was lack of oversight. Not only was the department itself at fault, but Congress as well, for failing in its duty to police the police.

"In all likelihood, if there had been vigorous oversight of Justice Department programs, and the FBI's use of informants, most of the events that are described in this report would not have occurred," the report says. "Unfortunately, however, there was a failure of oversight. The Justice Department failed to police itself, and Congress failed to do its job."

The report also directs sharp criticism of the Justice Department for blocking the committee's efforts to investigate the use of criminals as informants. In April, after the committee asked to speak with an informant, Robert Daddeico, the Justice Department claimed it needed more information to be able to identify and find him.

That was a "particularly curious" statement, the report says, because a Justice Department employee contacted Daddeico to tell him the committee wanted to interview him. A few days before the committee interviewed Daddeico, the FBI offered him a payment of $15,000, according to the report.

Rep. Marty Meehan, D-Massachusetts, who also had not seen the report, praised the committee for its work.

"I sat through committee hearings that revealed a history of serious mistakes in the use of criminal informants by members of the Boston FBI office. These hearings demonstrated the critical importance of changing the culture and practices that have permeated the bureau and undermined its credibility," he said in a statement.