Fifteen years after taking back Hong Kong amid a blaze of fireworks and patriotic fervor, China is battling what it sees as a subversive challenge: an academic survey showing that many in this former British colony identify little with China.

The survey, conducted last month by the University of Hong Kong, found that the number of respondents who view themselves as Hong Kongers is more than double the number who see themselves as Chinese and that bonds of shared identity with the mainland have grown weaker since Britain relinquished control in 1997.

Infuriated by the results, Chinese officials have orchestrated a campaign of denunciation — the latest blast in a barrage of verbal and written broadsides against alleged disloyalty in Hong Kong.

As a “special administrative region” within China, Hong Kong largely runs its own affairs under the “one country, two systems” formula enunciated by Deng Xiaoping, China’s late paramount leader. It has its own legal system and currency, issues its own travel documents and allows free speech and other liberties unknown in the rest of China.

In recent months, however, Chinese officials and pro-Beijing media in the former colony have gone on the offensive against a host of public figures whose views they dislike, including pro-democracy politicians, an elderly Catholic priest, an anti-communist media tycoon and the U.S. consul general. Now, they have turned their fire on Robert Chung, the director of Hong Kong University’s Public Opinion Program.

Chung has been surveying Hong Kong identity since the territory’s return to China, and the results of his latest poll merely confirmed anecdotal evidence of a significant trend among residents: growing resentment toward — and a sense of separateness from — mainland Chinese.

On Sunday, hundreds of Hong Kongers protested outside luxury retailer Dolce & Gabbana after complaints that the store discriminated against locals in favor of mainlanders. An influx of shoppers from across the border has delighted Hong Kong retailers but stirred disquiet among ordinary people fearful that their city is being swamped by often-brash newcomers. Hong Kong has a population of about 7 million; the rest of China has more than 1.3 billion people.

A music video made in Hong Kong and posted last year on the Internet sneered at mainlanders as “locusts” who “shout in restaurants, hotels and stores” and show scant regard for the city’s more orderly ways.

Hong Kong news media, meanwhile, have been filled in recent weeks with reports of pregnant mainland women crossing the border to take advantage of Hong Kong’s superior medical system and a rule that babies born in the city have the right of abode here. Politicians of all stripes have demanded action to halt the flow amid warnings that Hong Kong’s health-care system can’t take the strain. The number of mainland women giving birth in Hong Kong emergency wards nearly tripled last year.

China’s sharp reaction

Although evidence of Hong Kongers’ fading sense of kinship with China has been mounting for some time, Beijing reacted with startling anger to Chung’s findings.

Hao Tiechuan, a senior official at the Chinese government’s liaison office here, called in selected local reporters and lambasted the study as “unscientific” and “illogical,” saying that because Hong Kong is now part of China, it is wrong to ask residents whether they consider themselves Chinese. Media controlled by the Communist Party then directed a torrent of abuse at Chung and his work.

“Chung’s survey has evil political aims,” the Wen Wei Po newspaper opined. The Hong Kong-based paper reviled Chung as a “slave of black political funding” and accused him of seeking to “divide Hong Kong people from their compatriots.”

Chung dismissed the allegations as a “Cultural Revolution-style smear campaign.”

The China Daily, a state-run mainland newspaper, ridiculed the survey as “preposterous” and “intent on messing up Hong Kong.” Other party-controlled media in Hong Kong suggested that Chung was being manipulated by foreign interests, including British spies, alleging contacts with David Ford, a former colonial official in Hong Kong with supposed ties to British intelligence.

“I do not know David Ford, and I have never met him,” Chung said.

China’s sharp reaction has sparked wary speculation here about its motives. One theory is that officials merely want to display tough nationalist credentials ahead of a leadership transition in Beijing this year. Others note the role of local politics: Hong Kong will get a new chief executive this year — chosen by a 1,200-member committee — and will then start preparations for a real election, with universal suffrage, scheduled for 2017.

Beijing, analysts say, wants to ensure that the expansion of democracy in Hong Kong doesn’t empower “hostile forces” or encourage discussion of what it views as taboo issues, one of the most sensitive of which is identity.

A distinct identity

Determined to uproot separatist sentiment in Tibet, Xinjiang and other regions with large non-Han Chinese populations, Beijing has long insisted that all citizens view themselves only as “Chinese.” Hong Kong is almost entirely Chinese in its ethnic and cultural makeup, but after being separated from China during 156 years of British rule, it has a distinct identity.

Surveys conducted by Chung’s unit at Hong Kong University show that identification with China increased somewhat after the 1997 handover but began to decline after peaking in 2008 when Beijing hosted the Olympic Games. Just 34 percent of those surveyed last month identified themselves as primarily Chinese, and 63 percent emphasized their Hong Kong identity.

Chung declined to speculate on why Hong Kong’s residents appear to identify less with China but said he stands by his findings.

“I am not a politician,” he said. “I will let history tell the true value of my work.”

Independent media have rallied to Chung’s defense and voiced alarm at China’s reaction. Instead of attacking Chung, the Ming Pao newspaper said, Beijing officials should ask why Hong Kong’s people “are growing cool towards China.”