(CNN) -- A videotape on a Russian Web site allegedly showing a State Department employee having sex with a prostitute is a "smear campaign" meant to discredit the man, a State Department spokesman said Thursday.
The State Department has said the tape allegedly showing an employee having sex with a prostitute is a fake.
The employee, Brendan Kyle Hatcher, denied any encounter with a prostitute to his superiors at the U.S. Embassy in Moscow, another State Department official said.
State Department spokesman Ian Kelly said the U.S. ambassador to Russia, John Beyrle, "supports" Hatcher, who remains at his job at the embassy.
Hatcher had previously worked in the sensitive area of religious and human rights in Russia, the spokesman said.
"Mr. Hatcher ... enjoys the full confidence of Ambassador Beyrle and fully intends to serve out the rest of his tour in Moscow," Kelly said at an afternoon briefing at the State Department.
The United States "deplores this type of campaign and use of the Internet to smear a foreign service officer of good standing," he added. Watch why the U.S. says the tape is doctored »
Beyrle was unequivocal in expressing his support in an interview with ABC News.
"Kyle Hatcher has done nothing wrong," he said. "Clearly, the video we saw was a montage of lot of different clips, some of them which are clearly fabricated."
A senior State Department official said, "It's a doctored tape and a set-up designed to implicate someone working as a liaison with religious and human rights groups in Russia."
The official said Hatcher, who is married, "was approached by Russians; they tried to blackmail him, but he did everything correctly," reporting the incident to his supervisors at the Embassy.
The tape then appeared on the tabloid newspaper Web site Compromat.ru and was picked up by other outlets. Diplomatic sources who declined to be named said Compromat.ru has a history of ties to Russia's security services.
Russia's Foreign Ministry had no comment when asked about the video.
Another senior State Department official, who has seen the video, said "it's clear to me that it's him," referring to portions showing Hatcher alone in the hotel room.
"But then the lights go down," and the footage from there on is faked, that official said.
The video of Hatcher in the hotel room was taken last year, "somewhere in Siberia," said the senior State Department official who watched the video.
It was shot in a hotel that Hatcher visited, the official said.
When questioned about the possible motivation for creating the video, the official said it's presumed "it was done because of his human rights work," in Russia.
The official doubted the incident will have any effect on U.S.-Russian relations and noted that the Kremlin and the Russian Foreign Ministry have both been "very cooperative" in the months since the footage came to light.
"The vast majority of people there are working toward better relations," the official said.
Another official said Hatcher is a "great officer" who, until last summer, was a political reporting officer focusing on religious freedom issues in Russia. The assignment lasts two years: one year in that specialty and a year on the visa-issuing line at the embassy.
Last year, this official said, Hatcher was the lead officer compiling the State Department's Religious Freedom report and was given an award for his work by the ambassador.
Another official confirmed that Hatcher received a meritorious honor award in 2009 and a group award in 2008.
Hatcher, one official said, worked with religious groups that are considered "outside the mainstream" in Russia, such as Protestants and non-Christians. Such faiths often face official and unofficial discrimination in the largely Russian-Orthodox society.
Another senior State Department official said, "there is a lot of inertia" among some special security services in Russia.
"They are pretty much unreconstructed," he said. The security services may have wanted to compromise Hatcher's ability to work with religious groups, he says, "or they may have wanted to throw a stick into the spokes" of the U.S.-Russia relationship.
"Some in Moscow," he said, "are looking to integrate with the West, and others are trying to stop that."
The officials asked not to be identified because they were not authorized to speak publicly about the matter.
CNN's Matthew Chance in Moscow and Paul Courson in Washington contributed to this report.