"Extremely low levels" of radioactive iodine have been detected in the air of seven more Chinese regions, including Beijing, but the materials pose no threat to public health, China's National Nuclear Emergency Coordination Committee said Thursday.

According to a daily statement issued by the committee, low levels of radioactive isotope iodine-131 were detected on Thursday in seven more regions including Beijing, Hunan, Liaoning, Shandong, Guizhou, Gansu and Qinghai, raising the total number of regions that reported radioactive materials to 25.

The other 18 provinces, municipalities and autonomous regions include Shanghai, Tianjin, Chongqing, Hebei, Shanxi, Inner Mongolia, Jilin, Heilongjiang, Jiangsu, Anhui, Zhejiang, Fujian, Henan, Guangdong, Guangxi, Sichuan, Shaanxi, and Ningxia.

The material is believed to have drifted to China by air from the quake-damaged Fukushima Daiichi Nuclear Power Plant in Japan.

However, the amount of radiation these materials have were below one hundred-thousandth of the average annual exposure level to natural radioactive sources such as rocks, soil, food and the sun, the committee said.

No protective measures need to be taken against contamination from the material, 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 and the Ministry of Environmental Protection, according to the statement.

Low levels of radioactive isotope iodine-131 from the quake-damaged nuclear power plant were first detected in China in the northeastern Heilongjiang Province on March 26.