New York (CNN) Hackers associated with the Chinese government compromised websites frequented by ethnic minority Uyghurs earlier this year, programming them to install monitoring implants to spy on the phones of users that visited them, according to researchers.

Some of the sites had the capability to infect both Android phones and iPhones, a source familiar with multiple companies' research on the sites, some of which is not public, confirmed to CNN. It wasn't clear, however, that the sites were capable of hacking both types of phones at the same time.

The findings highlight just how powerful cyberespionage campaigns can be when governments with sufficient resources decide to spy on particular groups by compromising entire categories of websites and indiscriminately hacking the mobile users who access them.

The broad approach of the attacks could easily be repurposed for other groups, like Hong Kong protesters, said Adam Segal, the director of the Digital and Cyberspace Policy program at the Council on Foreign Relations.

"These are all outwardly facing websites, so you would expect that the capacity would be able to do the same to Taiwanese parties or Hong Kong student websites, or any other websites," Segal told CNN.

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