WASHINGTON - Federal prosecutors in Arizona have opened a preliminary investigation of a camping trip Congressman Jim Kolbe, R-Ariz., took 10 years ago that included two teenage congressional pages, a Justice Department spokesman told NBC News. NBC News first reported on the camping and rafting trip on Tuesday.

A spokesman for the Justice Department in Washington said that the U.S. attorney in Arizona has started a "preliminary assessment" of the trip, after an unidentified source made allegations about the congressman's behavior on the expedition.

"The U.S. attorney is looking into allegations about the congressman taking a trip with the two pages," the spokesman said.

As NBC News first reported, Kolbe took a tour down the Grand Canyon in July 1996 with a group that included two 17-year-old males who had recently left the congressional page program.

National Park Service employees also were on the three-day trip, along with several Kolbe staffers and the congressman's sister. Kolbe, the only openly gay Republican legislator in both houses of Congress, had not acknowledged his homosexuality publicly at the time.

Kolbe's office issued a statement to NBC News denying that anything improper had happened. "The rafting trip back in 1996 consisted of five current staff, two former pages, and his sister," a spokeswoman for Kolbe said. "There is absolutely no basis and no truth to any [allegations of] inappropriate behavior."

The FBI, which normally would be expected to carry out the actual investigation on behalf of the local U.S. attorney's office, would not comment.

Wyn Hornbuckle, a spokesman for the U.S. attorney in Arizona, said, "We are aware of the reports about the trip and we're responding appropriately."

Kolbe's spokeswoman said she was not aware of the U.S. attorney's initial inquiry.

NBC News interviewed several people who were on the trip, and their accounts vary. One participant, who requested anonymity, said he was uncomfortable with the attention Kolbe paid to one of the former pages. He was "creeped out by it," he said, adding that there was a lot of "fawning, petting and touching" on the teenager's arms, shoulders and back by Kolbe.

However, Gary Cummins, the deputy superintendent of the Grand Canyon National Park at the time — and who also was on the trip — said he did not see anything inappropriate take place.

NBC also interviewed the two former pages, who are now in their late 20s. One of them said that Kolbe was a gentleman and never acted in an improper fashion. He recalled that the pair spent time in Kolbe's house at one point — and briefly were alone with him on the trip — and that Kolbe always acted professionally and decently.

The other would not comment on Kolbe's behavior during the trip or characterize it in any way.

"I don't want to get into the details," he said. "I just don't want to get into this... because I might possibly be considered for a job in the administration."

However, the former page — who is the one to whom Kolbe allegedly paid special attention — said he had a "blast" on the trip and did not report anything improper to his parents or any House officials after the trip. He said he has a favorable impression of the page program to this day and likes Kolbe.

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