Radioactive iodine-131 continues to be at "extremely low levels" over China, according to the latest reports.

Traces were detected over some areas of the 31 provincial-level regions on the Chinese mainland yesterday.

In addition, trace levels of caesium-137 and caesium-134 were detected in the air in Beijing, Tianjin, Shanxi, Inner Mongolia, Shandong, Henan, Guizhou and Ningxia.

But they pose no threat to public health or to the environment, China's National Nuclear Emergency Coordination Committee said.