(Bloomberg) -- Thousands of Hong Kongers are downloading a U.K. government smartphone app that lets them apply for British visas, making it one of the territory’s most popular downloads and fueling a dispute between London and Beijing.

The U.K. Immigration: ID Check app has been the second-most-popular download for iPhone users in Hong Kong since it became available on Tuesday, according to tracking firm Sensor Tower. It was third in the local Google Play Store chart early on Thursday, behind an app from McDonald’s Corp. and a virus-tracing program from the Hong Kong government.

Britain has angered China by offering some residents of its former colony longer stays and a pathway to citizenship in response to a national security law Beijing imposed on the territory in June. The app lets visa applicants confirm their identities by scanning passports and faces. They can also apply in person, according to the U.K. Home Office, which is running the system.

The British government says thousands of eligible people have applied for the new visa program, which went into effect on Jan. 31. The Chinese Embassy in London has expressed “grave concern and strong opposition” to the policy, and said it would respond with counter-measures.

The app’s been downloaded approximately 26,000 times globally, with nearly 5,000 of those on Tuesday when it opened to Hong Kongers, according to estimates from Sensor Tower. Although it was launched last year for other visa applications, and simply opened to Hong Kong applicants this week, as many as 82% of its downloads have come from the territory, the research firm said.

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