A salesman at a pharmacy in Beijing shows a box of iodine tablets on Wednesday.

Some Chinese are buying iodine tablets to protect themselves against possible radioactive contamination resulting from the escalating nuclear emergency in Japan.

Authorities in China are meanwhile conducting more monitoring and inspections in the hope of persuading the public to remain calm amid growing concerns over radiation leaks.

Radiation levels in Japan have risen in recent days, following a succession of explosions that rocked the Fukushima Daiichi nuclear plant on the country's northeast coast. Many Chinese have begun to worry that the radiation will move toward the mainland and have sought protection from iodine pills, which help prevent the human body from absorbing radioactive materials.

"We sold out of cydiodine tablets last weekend - more than 20 packs in all," said an employee surnamed Liu at the Zhongyang pharmacy in Beijing's Chaoyang district. "Before the earthquake struck Japan, we had barely sold any."

Liu said most people who ask for the tablets have relatives or friends living in eastern coastal cities, which are closer to Japan.

Liang Ping, a 56-year-old retired doctor in Shanghai, said she went to more than 10 pharmacies and found that the cydiodine tablets once stocked by each had been sold out. So she turned to a friend working in a hospital, who bought 10 packs of the tablets for her.