HONG KONG -- It turns out that train tracks in Tibet aren't where the antelope play.

Earlier this week, Xinhua, China's state-run news agency, issued an unusual public apology for publishing a doctored photograph of Tibetan wildlife frolicking near a high-speed train.

The deception -- uncovered by Chinese Internet users who sniffed out a Photoshop scam in the award-winning picture -- has brought on a big debate about media ethics, China's troubled relationship with Tibet, and how pregnant antelope react to noise.

The antelope imbroglio began in the summer of 2006. The Chinese government was celebrating its latest engineering feat, and an enthusiastic wildlife photographer from the Daqing Evening News was camped out on the Tibetan plateau eating energy bars and waiting for antelope to pass.

On July 1, 2006, in an event scheduled to coincide with the Communist Party's 85th birthday, Chinese President Hu Jintao hosted the launch of China's train to the "roof of the world." The $4 billion Qinghai-Xizang railway -- a remarkable system that transports passengers to an altitude (16,000 feet) so high that ballpoint pens can explode en route from the air-pressure change -- traverses 1,200 miles of rugged terrain to connect the rest of China to the remote Tibetan plateau.

The train, which soon brought many visitors to the pristine homeland of Tibetan Buddhists, became a flash point for China's long simmering tensions with Tibet. During construction, it drew fierce protests from environmentalists who said it would threaten the breeding grounds of the chiru, an endangered antelope species found mainly in China.

When the train service began, a remarkable photograph appeared in hundreds of newspapers, and it eased environmental concerns. The picture, captioned "Qinghai-Tibet railway opens green passage for wildlife," featured dozens of antelope galloping peacefully across the Tibetan landscape, unfazed as the gleaming silver train raced beside them.

The photo was the work of Liu Weiqing, a 41-year-old photographer who had been camped with his Jeep on the Tibetan plateau since March, as part of a highly publicized series by the Daqing Evening News, a regional newspaper, to raise awareness of the rare Tibetan antelope. Mr. Liu was also under contract with Xinhua to provide photos for China's largest government-run news service.

"One man, one car, one year...and a campaign to protect Tibetan antelope," he wrote on his blog describing the project.

Once nearly wiped out by poachers who made shawls from its wool, the chiru's numbers have increased in recent years, and the knobby-kneed bovid has emerged as a symbol of China's environmental-protection efforts. Yingying the Tibetan Antelope is one of the five official mascots of the 2008 Beijing Olympics.

Some antelope lovers knew from the start that something was wrong with Mr. Liu's photo. "I was really shocked when I first saw the photo," says Yang Xin, of the antelope protection group Green River. For starters, he says, many of the antelope in the picture appeared to be pregnant and there were no young with the herd. That was a tip-off because many antelope would have given birth before late June when the photo was supposedly taken.

In late 2006, Mr. Liu's picture was declared a top 10 "photo of the year" by CCTV, China's state-run television network. Mr. Liu appeared in fatigues on national TV and described waiting in a pit for eight days for the antelope to pass at precisely the same moment as the train.

"I wanted to capture the harmony among the Tibetan antelope, the train, men and nature," he told the audience, standing on stage in front of a big projection of the photo.

Media critics say the photo's deeper message was hard to miss. "It's such a perfect propaganda photo," says David Bandurski a researcher at the University of Hong Kong China Media Project. "They don't tend to give journalism prizes to reports that rock the boat."

Other photographs that took home awards that night included "Facing a harmonious future," a picture of Chinese President Hu posing with world leaders, and a "A trip to apologize," a picture of a Japanese monk apologizing to China for Japanese atrocities in World War II. CCTV didn't reply to inquiries about its criteria for photo awards.

Suspicions about the photo became public last week after Mr. Liu's photograph was displayed in Beijing's subway system. An anonymous Chinese Internet user going by the screen name Dajiala raised questions about the photo's authenticity on one of China's largest photography Web sites. Dajiala, a photographer who claimed to idolize Mr. Liu, said he was studying a copy of the photo posted on Beijing's Line 5 subway platform when he rubbed some dust off it and noticed something odd.

"At the bottom of the photograph, there was a very obvious line," he wrote. "I examined it very carefully and it was obviously the stitching of two different images....Was this decisive moment just a simple Photoshop trick?"