IBM said Thursday it has developed a system for a Chinese mobile phone operator that blocks spam text messaging, but denied the software could be used as a censorship tool.
The US software giant said the system had been developed for a subsidiary of China Mobile, the world's biggest telecom operator.
"The anti-spam texting system IBM developed for Fujian Mobile is solely designed to improve the performance of telecommunications networks by blocking high network traffic associated with spam SMS activity," IBM spokeswoman Harriet Ip told AFP.
"It is not designed to filter content or censor data and it is not technically capable of doing so."
"Its sole purpose is to improve mobile phone customer service by eliminating meddlesome spam text messages."
No other companies had plans to install the system, she added.
Ip's comments came after the Financial Times reported that IBM's anti-spam software could be used by the Chinese mobile phone operator to censor text messages.
China is the biggest mobile phone market in the world, with more than 750 million subscribers, official figures show.
Beijing, which strictly censors the Internet and other media, has launched a crackdown on "illegal short messages", state media has reported.
Explore further: Android gains in US, basic phones almost extinct