Authorities found more than 50,000 counterfeit mobile phone batteries in an underground factory in Haizhu District on Friday, the Guangzhou Daily reported.

The Haizhu District trade and commerce bureau staff raided the four-story factory in Xiyao Village after receiving a report from an informant.

The factory was the biggest counterfeit battery factory the bureau uncovered this year, said an official.

All the batteries were counterfeits of famous brands. The packages of the batteries resembled those of the brands.

The factory was very well organized. The first and second floors were warehouses, the second floor was the workers' canteen and dormitory, and the workshop on the fourth floor was hidden behind heavy window curtains.

There were more than 30,000 completed mobile phone batteries on the second floor and more than 20,000 half-completed mobile phone batteries on the fourth floor. If the batteries sold to the market as authentic, they would worth more than 5 million yuan (US$616,523).

About 20 workers worked in the factory. They refused to reveal their boss' name, saying they had no clue about his identity. They did not stop working even when trade and commerce bureau staff raided the factory.

Reporters of the Guangzhou Daily dialed the mobile phone numbers on a name card which seemed to have been left by the boss, but found the numbers were invalid.

It was unclear when the factory opened, or how many batteries had been sold. Neighbors said the owner of the building had moved out to a new house. The building's door was closed most of the time. Neighbors saw people transporting goods in or out of the building at midnight.

Authorities said they would destroy the batteries after doing some tests on them. Police will continue to investigate the case.

Insiders said batteries produced in such a factory would become useless after being used for a couple of times, and might even explode.

(Shenzhen Daily August 23, 2005)