Stories of bosses secretly installing surveillance cameras in bathrooms have alarmed many working women.

The popularity of cellphones with a camera function further worries patrons who frequent saunas and swimming pools.

But people anxious about their privacy can stop worrying.

A Tsinghua University researcher has invented a counter-surveillance gadget called a "detective dog", reports Beijing Evening News.

When it senses electronic waves in the air, the match-box-size gadget emits a warning that means a surveillance camera is within 10 metres, said Tang Tai, who works in the lab of the Security Technology department at Tsinghua University.

A friend whose wife travels frequently requested the invention, Tang said.

Though it is quite expensive for most Chinese at 1,000 yuan (US$120), Tang is having difficulty filling orders from a great number of businessmen and women.

(China Daily HongKong edition 03/04/2003)

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