WASHINGTON – Federal prosecutors are investigating whether employees of the private security firm Blackwater USA illegally smuggled into Iraq weapons that may have been sold on the black market and ended up in the hands of an American-designated terrorist organization, officials said yesterday.

The U.S. Attorney’s Office in Raleigh, N.C., where Blackwater is based, is handling the investigation with help from Pentagon and State Department auditors who have concluded there is enough evidence to file charges, the officials told The Associated Press.

The chief Federal prosecutor for the eastern district of North Carolina, George Holding, and a spokeswoman for Blackwater did not return calls seeking comment today. Pentagon and State Department spokesmen declined to comment.

Officials with knowledge of the case said it is active, although at an early stage. They spoke on condition of anonymity due to the sensitivity of the matter, which has heightened since 11 Iraqis were killed Sunday in a shooting involving Blackwater contractors protecting an American diplomatic convoy in Baghdad.

The officials could not say whether the investigation would result in indictments, how many Blackwater employees are involved or if the company itself, which has won hundreds of millions of dollars in government security contracts since the 2003 invasion of Iraq, is under scrutiny.

In today’s editions, The News & Observer of Raleigh reported that two former Blackwater employees — Kenneth Wayne Cashwell of Virginia Beach, Va., and William Ellsworth “Max” Grumiaux of Clemmons, N.C. — are cooperating with federal investigators.

Cashwell and Grumiaux pleaded guilty in early 2007 to possession of stolen firearms that had been shipped in interstate or foreign commerce, and aided and abetted another in doing so, according to court papers viewed by The Associated Press. In their plea agreements, which call for a maximum sentence of 10 years in prison and a $250,000 fine, the men agreed to testify in any future proceedings.

Calls to defense attorneys were not immediately returned this evening, and calls to the telephone listings for both men also were not returned.

The News and Observer, citing unidentified sources, reported that the probe was looking at whether Blackwater had shipped unlicensed automatic weapons and military goods to Iraq without a license.

The paper’s report that the company itself was under investigation could not be confirmed by the AP.

According to officials in Washington, the investigation grew from internal Pentagon and State Department inquiries into American weapons that had gone missing in Iraq. It gained steam after Turkish authorities protested to America in July that they had seized American arms from the outlawed Kurdistan Workers Party, or PKK, rebels.

The Turks provided serial numbers of the weapons to American investigators, said a Turkish official.

The Pentagon said in late July it was looking into the Turkish complaints and an American official said FBI agents had traveled to Turkey in recent months to look into cases of missing American weapons in Iraq.

Investigators are determining whether the alleged Blackwater weapons match those taken from the PKK.

It was not clear if Blackwater employees suspected of selling to the black market knew the weapons they allegedly sold to middlemen might wind up with the PKK. If they did, possible charges against them could be more serious than theft or illegal weapons sales, officials said.

The PKK, which is fighting for an independent Kurdistan, is banned in Turkey, which has a restive Kurdish population and is considered a “foreign terrorist organization” by the State Department. That designation bars American citizens or those in American jurisdictions from supporting the group in any way.

The North Carolina investigation was first brought to light by State Department Inspector General Howard Krongard, who mentioned it, perhaps inadvertently, this week while denying he had improperly blocked fraud and corruption probes in Iraq and Afghanistan.

Mr. Krongard was accused in a letter by Rep. Henry Waxman, Democrat of California, chairman of the House Oversight and Government Reform Committee, of politically motivated malfeasance, including refusing to cooperate with an investigation into alleged weapons smuggling by a large, unidentified State Department contractor.

In response, Mr. Krongard said in a written statement that he “made one of my best investigators available to help Assistant U.S. Attorneys in North Carolina in their investigation into alleged smuggling of weapons into Iraq by a contractor.”

His statement went further than Mr. Waxman’s letter because it identified the state in which the investigation was taking place. Blackwater, based in Moyock, N.C., is the biggest of the State Department’s three private security contractors.

The other two, Dyncorp and Triple Canopy, are based in Washington’s northern Virginias suburbs, outside the jurisdiction of the North Carolina’s attorneys.