Residents of Ili Kazak Autonomous Prefecture in Northwest China's Xinjiang Uyghur Autonomous Region have been required to register their biometric information, such as DNA, when applying for passports since June 1.

Ili's Exit and Entry Administration is requiring residents to have their fingerprints, DNA, voiceprint and three-dimensional image collected in local police stations when they apply for passports or travel permits to Hong Kong, Macao and Taiwan, Ili Daily reported Friday.

"In fact, all residents in Xinjiang have always had to record their biological information to apply for passports, including fingerprints and DNA," an employee of the Xinjiang branch of China International Travel Service, a major travel agency in China, told the Global Times on Tuesday.

The number of certificates issued by the Ili Exit and Entry Administration skyrocketed from 20,000 in 2014 to 100,000 in 2015, and authorities said they expect the number of certificates issued this year to exceed 20,000.