South Korea, the United States and Japan have completed work on a three-way communication hotline, the Yonhap news agency reported on Tuesday, citing a senior Seoul official, in a further sign of growing trilateral security cooperation.

The hotline comes at a time of military tensions with North Korea and China's growing regional influence. The three countries' leaders announced a commitment to consult each other in times of crisis at a summit in Camp David in August.

Technical tests of the system have been completed, Yonhap said, citing the anonymous source. The hotline is to be used by the leaders or their top national security advisers in times of security crises, it said.