In the latest development in the controversy over an Obama administration gun-smuggling investigation, the head of the Justice Department's criminal division said Monday he regrets not alerting the department's leadership to problems in a similar gun-smuggling probe under the Bush administration.

Assistant Attorney General Lanny Breuer said he knew in April 2010 that investigators in the 2006 Bush-era probe had allowed hundreds of guns to be transferred to suspected arms traffickers _ the same tactic that Republicans are criticizing the Obama's administration for using in Operation Fast and Furious.

When allegations about Fast and Furious surfaced early this year, the Justice Department told Congress that the department makes "every effort" to seize weapons that have been purchased illegally _ a statement undermined by the existence of the earlier Bush-era probe.

Breuer said he made a mistake in not telling Attorney General Eric Holder and Deputy Attorney General James Cole about the earlier probe called Operation Wide Receiver in which the so-called gun-walking tactic was used.

Breuer's admission came as the Justice Department sent documents to Capitol Hill that detail his knowledge of the earlier investigation. The House Oversight and Government Reform Committee, led by Republican Rep. Darrell Issa of California, and the Justice Department's inspector general are looking into the gun-walking tactics used in Fast and Furious.

"Knowing what I know now ... I wish that I had gone upstairs" and told Holder and Cole, the department's two top officials, Breuer said in an interview with The Associated Press. "As Wide Receiver makes its way to my office, it looks like ATF permitted guns to go to Mexico even though they had the legal authority and the ability" to intercept them.

"Early this year you have an ATF leadership that adamantly and explicitly says that guns were not walking," Breuer said in explaining why he didn't alert department higher-ups about the older probe.

"I simply literally do not draw the connection" early this year between the two operations, said Breuer, given the denials about gun-walking and given that "I don't have intimate knowledge of Fast and Furious and frankly I'm dealing with all the things one does in the criminal division every day."