BEIJING, March 30 (Xinhua) -- China's food and drug safety watchdog on Friday urged intensified supervision and inspections to ensure the safety of health foods, especially those made of spirulina.

　　The State Food and Drug Administration (SFDA) last month organized research to examine levels of heavy metal elements, such as lead, arsenic and mercury, in spirulina-based health food products, the administration said in a statement on its website.

　　The inspection teams found that there were three kinds of counterfeit spirulina products on the market and that some samples of spirulina health foods produced by the "Fujian Xingfulai Biotechnology Company" contained excessive lead and arsenic, according to the statement.

　　Heavy metal content in samples from other manufacturers in the examination were within the limit of the national standard, the statement added.

　　It also said that the SFDA has ordered serious punishment for the violators involved.

　　Spirulina, a kind of protein-rich cyanobacterium, is commonly used as a dietary supplement.

　　Moreover, the statement clarified that according to the national food safety standard and relevant standards of the Ministry of Health and the SFDA, foods with spirulina or other algae as the major ingredient are subject to a different lead limit, which allows a maximum of 2mg of lead per kg, whereas the ceiling for lead contents in other food products is only 0.5mg per kg.