Minimal amounts of radioactive material from a crippled Japanese nuclear power plant continued to be found in most Chinese regions on Friday, according to China's National Nuclear Emergency Coordination Committee.

Trace levels of radioactive isotope cesium-137 and -134 were detected in the air of at least 24 of the Chinese mainland's 31 provincial-level regions on Friday.

Cesium-137 and -134 were detected in many regions, including Beijing, Shanghai, Tianjin, Chongqing, Hebei, Shanxi, Inner Mongolia, Liaoning, Jilin, Heilongjiang, Jiangsu, Zhejiang, Anhui, Fujian, Jiangxi, Shandong, Henan, Hubei, Guangdong, Hainan, Sichuan, Shannxi, Ningxia, Qinghai, Gansu and Xinjiang.

"Extremely low levels" of another radioactive isotope, iodine-131, were detected in the air over some areas of all provincial-level regions except Yunnan.

Similar levels of iodine-131 were also found on several kinds of vegetables in Beijing, Zhejiang, Shandong, Hunan, Guangdong, and Hainan.

The radioactive materials pose no threat to public health or to the environment, according to a daily statement issued by China's National Nuclear Emergency Coordination Committee Friday.

The materials are believed to have traveled by air to China from the quake-damaged Fukushima Daiichi Nuclear Power Plant in Japan.

No protective measures need to be taken against contamination from these materials, said the statement.

The committee's conclusion was based on monitoring and analysis results from the Beijing-based Regional Specialized Meteorological Center affiliated with the World Meteorological Organization and the International Atomic Energy Agency, the State Oceanic Administration, the Ministry of Environmental Protection and the Ministry of Health, according to the statement.

Low levels of iodine-131 were first detected in northeastern China's Heilongjiang Province on March 26.