More than 15,000 students have quit school in Hong Kong, official data shows as families flee the territory owing to a new national security law imposed by China.

Educators warn the figure may continue to increase.

Official data obtained by the South China Morning Post show that 690,965 students were enrolled in primary and secondary schools as of October 2020 - down by more than 15,000 from 706,422 registered in 2019.

The travel restrictions and months of suspended in-class learning have affected a number of students who live just across the border in mainland China but study in Hong Kong.

Kevin Yeung Yun-hung, Secretary for Education, promised officials would address the issue, SCMP reported.

"Hong Kong is a free society," Yeung said. "Of course there are people leaving Hong Kong. They are free to make these choices. In terms of the changes in the number of students, we've been staying in contact with schools...If the changes are long-term and structural, we will think of long-term solutions."

Some educators feared that the student departure could be worse than previously assumed, pointing out that the survey neglected to account for the most recent wave of migration.

Several Western countries, particularly the U.K., have offered favorable resettlement terms to Hong Kong citizens after China attempted to suppress pro-democracy rallies by passing a law that criminalizes practically all dissent.

Beginning Jan. 31, they might seek to live and work in the U.K. and, after six years, petition for citizenship. During the first two months of the initiative, more than 34,000 Hong Kong residents applied.

This means that thousands of families, particularly those with more means, are abandoning the territory, withdrawing pupils and leaving some schools.

Following the adoption of the national security law in June 2020, which prohibits acts of secession, subversion, terrorism and collusion with foreign forces, the U.K., Australia, and Canada have all announced new immigration options for Hong Kong residents.