China is marking a step forward in its efforts to discourage the use of nuclear weapons. A ceremony was held in the city of Guangzhou to mark the certification of four stations that monitor for nuclear weapons tests. Our reporter Ge Yunfei has more.

Over two decades ago, most of the world's nations negotiated the The Comprehensive Nuclear-Test-Ban Treaty, or CTBT. It's a ban on nuclear weapons tests, geared toward better preventing explosions. A key component is an international system made up of over 300 monitoring stations. Two years ago, China's first radionuclide station was certified. And on Tuesday, Dr. Lassina Zerbo, head of the CTBT Organisation, visited China's southern city of Guangzhou and granted certifications to four other Chinese monitoring stations.

LASSINA ZERBO, EXECUTIVE SECRETARY COMPREHENSIVE NUCLEAR-TEST-BAN TREATY ORGANIZATION  "The international monitoring system and comprehensive test responsibilities relying on the experts in China, with their skills and technical capabilities to build us a verification regime to support a world free from nuclear test. " 

GE YUNFEI GUANGZHOU" Everyday, the Guangzhou station will collect one air sample like this one, and analyze it to detect if there is any radioactive substances. And the data will be sent back to the International Data center in Vienna through this machine. "

SHI ZHONGJUN, AMBASSADOR PERMANENT MISSION OF CHINA TO THE UNITED NATIONS IN VIENNA "China was one of the first countries to sign the Comprehensive Nuclear-Test-Ban Treaty. The certification of these four stations fully exhibits China's responsible attitude in realizing its commitment."

Ambassador Shi said China will continue to take a more active and progressive role in pushing forward a world free of nuclear tests and weapons. Ge Yunfei, CGTN, Guangzhou.