A YouTube video featuring a man who presented himself as an American gay rights activist disillusioned with the latest Gaza flotilla campaign has been exposed as a hoax.

The man in the video, who introduced himself to viewers as Marc and claimed that the organizers of the latest flotilla of ships bound for Gaza had rejected his offer to mobilize a network of gay activists in support of their cause, was identified as Omer Gershon, a Tel Aviv actor involved in marketing, by the Electronic Intifada, a pro-Palestinian Web site.

As my colleague Ethan Bronner explains, pro-Palestinian activists, including the prominent American author Alice Walker, are planning to sail a flotilla of small ships from European ports toward Gaza to protest Israel’s naval blockade of the Palestinian territory.

Just hours after the supposedly homemade video was uploaded to YouTube on Thursday, Benjamin Doherty of the Electronic Intifada pointed out that it had suspiciously high production values — most obviously, lights and what is known as B-roll — and was attributed to an activist calling himself Marc Pax, who seemed to have no other online presence.

While it remains unclear who produced the video, and Mr. Gershon has not responded to a request for comment, bloggers were quick to point out that people in three different Israeli government offices promoted it on Twitter soon after it was posted online.

As the blogger Max Blumenthal reported on Friday, one of the first people to draw attention to the video was Guy Seemann, who is an intern in the office of Benjamin Netanyahu, the Israeli prime minister.

The same day, the Israeli government’s press office advised its Twitter followers to watch the video and follow Mr. Seemann’s feed.

Over the weekend, Israel’s Ministry of Foreign Affairs also posted a link to the video on its official Twitter feed.

After the Electronic Intifada revealed that the man in the video was an actor, the Israeli press office deleted its original message from Twitter and posted a new one, apologizing for having promoted “an apparent hoax.” The press office added, “We were duped.”

A spokesman for the Israeli prime minister told The Lede: “Mr. Seemann is a 25-year-old who is interning in our office. His tweet was a mistake on his part. It was done without authorization and without approval. His mistake has been pointed out to him.” Mr. Seemann, who denied that he had had any role in the production of the video and said that it had been sent to him by “a friend,” has deleted his entire Twitter feed. He declined to put The Lede in touch with the friend who informed him about the video.

Yigal Palmor, a spokesman for the Ministry of Foreign Affairs, told The Lede that its Twitter feed was also edited to remove a link to the video after it was “revealed to be not a documentary but rather a mockumentary.”

None of the Israeli officials responded to a request to comment on the accusation by pro-Palestinian bloggers that the government might have played a role in the production of the video.

The foreign ministry appears to have become aware of the video from a message posted on Twitter by David Saranga, a diplomat who also teaches at Israel’s Asper Institute for New Media Diplomacy.* According to the institute’s Web site, Mr. Saranga has worked with students who were learning to use “traditional P.R. and marketing techniques to distribute” content about Israel “around the world, along with more Web-based approaches such as guerrilla marketing.”

Ali Abunimah, the Palestinian-American founder of the Electronic Intifada, suggested on Twitter that the video hoax was not a prank but part of a public relations campaign to support the Israeli government’s naval blockade of Gaza by seeking to tarnish the Gaza flotilla activists as homophobic.

While there is no evidence of homophobia by the activists, and indeed some of the participants in the new flotilla are gay, the Israeli actor featured in the video has recently worked with a producer who appears to be opposed to the flotilla campaign. The actor, Omer Gershon — who is a minor celebrity in Tel Aviv — recently directed and appeared in this commercial for Puma, which was produced by Elad Magdasi. The commercial is currently featured on the home page of Mr. Magdasi’s YouTube channel, which also features a link to videos made by “a nonprofit Israel advocacy organization” called Stand With Us.

The Stand With Us YouTube channel currently features a new video that argues that Israel’s military “lawfully enforces a naval blockade on the Gaza Strip,” which is necessary “to protect Israeli civilians from attacks by the terrorist organization Hamas.”

According to Stand With Us, the organization’s work “ensures that Israel’s side of the story is told.” Its YouTube channel also features a recent testimonial from Mr. Netanyahu, congratulating the organization “for marking another successful year of defending the truth.” Mr. Netanyahu told the group, “In creatively adapting to the online world, you are staying one step ahead of adversaries who are working day and night to delegitimize Israel.”

Update 1: Dina Kraft, a freelance journalist who has contributed to The Times, writes from Israel to point out that she has interviewed Omer Gershon in the past and tried to call him on Tuesday, but was unable to reach him. Ms. Kraft interviewed Mr. Gershon in September, 2009, as part of her research for this Times article about Tel Aviv. At the time, he was helping to run a popular nightclub in the city called Zippy Trippo.

In that article, Ms. Kraft pointed to Zippy Trippo as an example of “Tel Aviv’s ability to reinvent itself.” The underground club, she explained, had been just one year earlier, “a listening post for the Shin Bet, Israel’s internal security service, dubbed by its workers as the Facility.”

Update 2: On Tuesday, an Israeli government official who spoke on condition of anonymity said that while similar efforts to forge what he described as “people to people” diplomacy have been undertaken by various government agencies, as far as he knew the prime minister’s office was not behind this specific video.

Also on Tuesday, the Israeli newspaper Haaretz reported that it “sent the prime minister’s office a series of questions inquiring whether the office was involved in the production of the video in any way. The premier’s office in response did not deny that that the government was involved in the video’s production.”

Finally, the organization Stand With Us said in a statement posted on Twitter: “We are not associated in anyway whatsoever with the maker of this fraudulent video.”

Update 3: A further clue as the hoax video’s origins appeared on Wednesday. As Max Blumenthal reported on Friday, one of the first people to promote the hoax video online seems to have been Neil Lazarus, a communications expert who claims on his professional Web site to have advised both the Israeli prime minister’s office and the Israeli ministry of foreign affairs.

That Mr. Lazarus posted the video on his Facebook wall is known because one of his Facebook friends, Elan Miller, found it there and shared it with his friends on the social network about 6 hours after it was first posted on YouTube.

On Wednesday, a blogger at the Electronic Intifada told The Lede that someone in Mr. Miller’s Facebook network said that the video had just 35 views on YouTube shortly after it was shared by Mr. Miller late Thursday night.

That means that Mr. Lazarus was one of the first people to watch the video and then advise others to do so. He has not yet responded to a request to explain how it was that he found out about the clip so soon after it was posted and before it attained any popularity.

*This post was revised to clarify that David Saranga still serves as an Israeli diplomat. A spokesman for Israel’s ministry of foreign affairs confirmed that he is about to start a new position in Brussels. The message he posted on Sunday advising people to watch the video remains in his Twitter feed