Hong Kong, China (AFP) — Google said Thursday it does not manipulate search results, after Hong Kong's government said the tech giant had refused its demand to remove a popular protest song.

The controversy began after it emerged that links to the pro-democracy song "Glory to Hong Kong" appeared ahead of China's official "March of the Volunteers" when people searched for the city's anthem.

The song was accidentally played for Hong Kong athletes at two international sports events last month, prompting the demand from the Chinese city to remove it from search results.

"Google handles billions of search queries every day, so we build ranking systems to automatically surface relevant, high quality, and helpful information," the tech giant told AFP in response to a query about the anthem request.

"We do not manually manipulate organic web listings to determine the ranking of a specific page," it said in a statement.

Hong Kong leader John Lee said this week that Google had a "moral obligation" to respect a country's national anthem.

The Chinese Foreign Ministry backed Lee, saying internet companies "have a duty to deliver correct information to the public."

Google told AFP it was in contact with Hong Kong's government to explain "how our platforms and removal policies work."

"We do not remove web results except for specific reasons outlined in our global policy documentation."

Both Tang and Lee have argued that Google search results can be manipulated, citing the placement of ads and the deletion of certain results to comply with privacy laws in the European Union.