China's drug watchdog has found 12 percent of traditional Chinese medicine (TCM) materials and tablets in a random sample check to be substandard, saying the quality situation is "not optimistic."

Irregularities including artificial coloring, weight-increasing practices and contamination by counterfeit or substandard ingredients were found in 93 out of 772 batches of TCM materials and tablets, according to a statement released by the China Food and Drug Administration on September 23.

Sold by weight and mostly processed from plants and animals parts, TCM ingredients are often bulked up through deceptive practices such as soaking them in salt water to increase their weight and mixing them with similar but cheaper and less effective materials.

The statement noted that the products checked were randomly collected from TCM manufacturers, sellers and users across the country, adding that groups related to questionable products will be duly penalized by local drug administrations.