The Suzhou police's traffic and patrol department responded to public criticism of its recent bid for 21 iPhone 4s by saying the smart phone model is the only mobile device that meets its video monitoring system's requirements.

The department's deputy political commissar Tao Ren told a news conference on Friday that the 32GB iPhone 4s will be used to create a digitized transportation monitoring system, enabling police to remotely observe scenes before they arrive. He did not reveal when the monitoring system would become operational.

The iPhone 4 is the only device the department could find that is compatible with the high-definition video transfer system with which their patrol cars will be equipped, Tao said, adding the iPhone 4 has a longer recording duration than other mobile devices.

Public criticism of the "extravagant" purchase began when a netizen posted information about the bid on the major domestic Internet forum tianya.cn on Thursday. Many netizens voiced concerns about government organs using taxpayers' money to buy luxury electronic products.

The post revealed all public bidding offers listed on the Suzhou government's website.

"How dare they say only the iPhone 4 can satisfy their work requirements?" a netizen, who goes by Anqilong, wrote on his blog, "What nonsense".

Suzhou traffic and patrol department officials said the iPhone 4s they purchased are part of a two-year contract package, which is "much cheaper than buying standalone mobile devices".

The Suzhou controversy came after the public criticized the proposed purchase of seven iTouch 4s by the government of Fushun city, Liaoning province, on Dec 20. The government said the portable media players would be used for data storage.

The public bid was canceled after the online criticism.

"These events have revealed loopholes in government procurement procedures," Fudan University media research professor Zhou Baohua said.

"Fortunately, online supervision makes government procurements more transparent," Zhou said.