A Chinese city will spend $24,000 on Trojan horse computer software for monitoring mobile phones, state media reported Thursday, after a notice announcing the move inexplicably appeared on a local website.

According to the Global Times newspaper, police in the eastern city of Wenzhou plan to spend a total of 149,000 yuan ($24,000) on the software, which is "designed for unlocked iPhones and Android smart phones to monitor the saved call logs, messages, photos and other information".

A notice announcing the move was published last month on the website of the Wenzhou Economic and Technological Development Zone, the paper said.

Screenshots of a chart on the development zone's website detailing the purchase circulated Wednesday on China's popular Sina Weibo social network.

By Thursday, the document -- which some users speculated had been posted in a bid to increase government transparency -- had been taken down from the website.

A Trojan horse is a type of malicious code that can force computers or smartphones to relay information to a third party without the knowledge or consent of their owners.

China regularly proclaims itself a victim of hacking, and a foreign ministry statement last month declared that Beijing "opposes cyber attacks and cyber terrorism in all of its forms".

China's Internet users heatedly discussed the controversy, with some voicing concern about their online privacy.

"Technological surveillance measures are like a Pandora's box: once you open it, it's difficult to control," one Sina Weibo user wrote Thursday. "And what are the consequences if you lose control? Chilling."

Others defended the purchase as necessary for the police to protect the public.

"If they don't use a little bit of modern technology, how do you expect them to crack cases?" one user wrote.

Xiang Ligang, an IT industry observer, told the Global Times that such monitoring of smartphones is "normal" in China.

But Xiang added: "It is odd to see a publication on such purchase."