SHANGHAI - Wide debate has arisen over the video cameras and sound recorders that have been installed in as many as 6,000 taxis in Nanjing, capital of Jiangsu province.

Critics say the devices infringe upon privacy.

But Xu Hong, director with the Nanjing passenger transportation management office, said they are in fact meant to protect the safety of drivers and the rights of passengers.

The cabs' recorders will run 24 hours a day and their cameras will be able to take eight pictures a minute.

The sound recordings will be stored in a data collector inside the taxis while the images will be transferred using a global positioning system to the police and to transportation management authorities. If a taxi driver feels endangered, he can press an emergency button that will make the camera start recording uninterruptedly and then send a report to the police.

As many as 6,000 out of the 9,000 taxis in Nanjing are now using the system. Those that do not have it will be replaced in the next couple of years.

"In the future, all taxis in Nanjing will be protected by the system," Xu said.

Some passengers said they are worried the recordings will be misused in ways that infringe on their privacy.

"What if a driver records a passengers' private conversation?" said Wang Minjie, a 21-year-old college student in Nanjing. "What if a girl accidentally exposes her lingerie in the summer and that is caught by the camera?"

Wang said she and many of her friends think of the inside of taxis as being a private space, making it different from the inside of a bus or a subway.

Some taxi drivers also complained that they feel as if they are being "watched all of the time".

"I have to be very cautious about what I say and what I do in the car," said Zhu Xiaohuan, a local taxi driver.

Xu said passengers should not worry about their privacy in taxis because the recordings are highly confidential, well-protected and are not open to unauthorized browsing.

"The only people who can have access to these recordings are the police and transportation management authorities who have proven they have reasons for dealing with public safety or with passengers' complaints," Xu said.

The data can be also used as evidence to support or refute complaints made against drivers. Xu said drivers will be more eager to provide quality services with the devices in their cars because they will know that any inappropriate behavior will be recorded.

Some passengers said they welcome the measure, saying it will help to eliminate unpleasant experiences in cabs.

"At least drivers will know that they are being monitored and supervised by the police and traffic management authorities, so they might provide better service to the customers," said Gu Chun, who often takes taxis in Nanjing.

Xu said it is widely recognized that putting cameras on buses and long-distance coaches will help to deter crimes.

About 400 taxis in Hangzhou, capital of Zhejiang province, and 4,000 taxis in Zhengzhou, capital of Henan province, have also installed the devices.