More than 90 percent of the nation's private security companies are suffering personnel shortages, a police survey showed Thursday, fueling concern about possible shortfalls in staff for the 2020 Tokyo Olympics and Paralympics.

To address the issue, the National Police Agency said it is considering revising legal regulations and introducing an online training system for security guards, to reduce the hurdles for companies looking to hire staff.

The number of security firms and guards has remained nearly flat in the last few years, standing at around 9,400 and 540,000, respectively, as of the end of 2016.