Beijing - Skype, the online text message and voice service, acknowledged Friday that its Chinese partner had been archiving politically sensitive text messages.

Skype president Josh Silverman said the company was unaware that the internet chat of users in China, especially political discussions, was being stored on computer servers by Chinese mobile firm TOM Online, a unit of Hong Kong-based TOM Group Ltd.

In a statement, Silverman said the US company owned by auction giant eBay was "very concerned" about the monitoring and storage as well as a security breach that was discovered by Canadian researchers.

The messages and personal information was stored on insecure publicly-accessible servers together with the encryption key required to decrypt the data, found Ottawa-based Citizen Lab. TOM has since acted to make its servers more secure.

"It was our understanding that it was not TOM's protocol to upload and store chat messages with certain keywords, and we are now inquiring with TOM to find out why the protocol changed," added Silverman.

TOM-Skype made it publicly known in 2006 that it filtered text messages for politically sensitive words, such as "Tibet" or "democracy," and blocked transmission of those judged suspect and assured users that censored messages were discarded.

"It is common knowledge that censorship does exist in China and that the Chinese government has been monitoring communications in and out of the country for many years," said Silverman, adding that TOM, like every other communications service provider operating in China, has an obligation to be compliant if they are to be able to operate in China at all.

The regulations include the requirement to monitor and block instant messages containing certain words deemed "offensive" by the Chinese authorities, said Silverman.

Skype users from other countries communicating with one of the 70 million TOM-Skype registered users were also subject to having their communications monitored, however, stressed Silverman, if both users have standard Skype software the messages "are, and always have been, completely secure and private."

Nart Villeneuve, a senior research fellow at Citizen Lab, discovered the surveillance system when he used an analysis tool to monitor data generated by the TOM-Skype software, according to the New York Times.

Villeneuve found that when he typed a particular swear word into the text messaging program an encrypted message was sent to an unidentified internet address and then stored on TOM Online computers.

He discovered he could examine the messages online as they were readable with a simple Web browser. After encrypting the log files he found hundreds of records of messages that had been stored and could learn the user names as well as message content. (dpa)