As of last night, inspections by the Shanghai Food and Drug Administration had not turned up any of the tainted bottles.

Meanwhile, health authorities in a Zhejiang Province city where the bottles reportedly originated shut down several factories linked to the scandal.

The shoddy bottles surfaced first up in Shijiazhuang in northern China's Hebei Province, according to a recent report on China Central Television. On April 29 during a routine market spot check, officers from the city's industrial and commercial bureau found 10 boxes of Aibao brand bottles that were discolored and failed to carry proper manufacturing information, the TV report said.

Tests on the bottles determined they contained twice the level of hydroxybenzene allowed by law, according to the TV report.

Hydroxybenzene is a toxic chemical that dissolves in heated milk and can cause liver and kidney damage, authorities said.

The bottles were traced back to Yiwu City, Zhejiang Province, which is one of China's biggest small-commodities distribution centers.

CCTV reporters found the same baby bottles as those seized in Hebei at more than 10 wholesalers, along with several other brands that had similar discolorations.

A visit to the Yiwu factory where the bottles were made turned up alarming sanitary conditions.

Reporters also discovered bags full of plastic pieces. One factory manager said the material was being stored in sugar bags to conceal it from inspectors.

The manager said the factory used the reclaimed plastic because it was much cheaper than clean material: some 20,000 yuan (US$2,494) a ton compared with 30,000 yuan for the type of plastic that is authorized for use in food production.

CCTV said the bottle makers bought the recycled plastic - used compact discs - from processing plants in Cixi, another Zhejiang city.

After the report aired, investigators in Yiwu launched an inspection of the city's bottle factories and closed three manufacturing sites. They also sent samples of the raw materials to provincial authorities for testing, the Xinmin Evening News reported yesterday.