China's National Nuclear Emergency Coordination Committee said Thursday in its daily notice that no obvious change had been found in the levels of radioactive material in the environment and food samples in the Chinese mainland.

No protective measures need to be taken against contamination from these materials, the notice said, adding that a sample survey indicated no abnormality in drinking water.

As of 8:49 a.m. Thursday Beijing Time, no obvious changes in the situation had been observed and readings from on-site radiation monitoring posts at the quake-damaged Fukushima Daiichi Nuclear Power Plant in Japan remained stable, according to the notice, quoting the International Atomic Energy Agency's latest report.

The fact that the level of the nuclear incident was upgraded didn't mean that the incident itself had experienced "sudden changes," the notice added.

On April 11, the Japanese government widened the evacuation zone beyond the 20-km radius of the power plant, encouraging local residents to stay out of some areas 20 to 30 km from the nuclear complex due to health concerns.

According to the notice, the move was part of Japan's further efforts to limit possibly higher exposure to radiation in some surrounding areas.

The committee said it had urged Japanese authorities to report information on the nuclear incident to China "in a more comprehensive and accurate manner."

On Wednesday, China's Ministry of Health said "extremely low levels" of radioactive isotope iodine-131 had been detected in various kinds of vegetables in 12 provincial regions.

The ministry said the detected amounts pose no threat to public health.