Amazon has suspended the sales of all Blu smartphones over a new security concern.

Last week security firm Kryptowire demonstrated that software in some of Blu's devices was collecting data and sending it to servers in China without user's consent. The company then went on to demonstrate the issue to Amazon which includes Blu phones in its Prime Exclusive Phones program. At that time Amazon decided to suspend sales of the top selling phones.

Currently, if you visit the page for any Blu phone on Amazon you will see a message stating that it is "Currently unavailable."

"Because security and privacy of our customers is of the utmost importance, all BLU phone models have been made unavailable for purchase on until the issue is resolved," Amazon said in a statement to CNET.

The main application in question is known as Adups which is used for OTA (over the air) updates. The claims are that it is taking information from contacts, text messages and call logs and transmitting them to servers residing in China.

Blu issued a statement on Monday refuting the claims, and said that Tom Kaygiannis, VP of Kryptowire had stated that "the data collection is in line with BLU's Privacy Policy, and does not constitute any wrong doing by BLU." However, in a later statement to CNET, Kaygiannis said that he had not authorized Blu to make that statement on his behalf.

As to when Blu phones will return to the virtual shelves of Amazon is anyone's guess. The phones perform very well for the retailer, appearing in its top selling unlocked phone sales charts on a regular basis. Amazon is sure to want to return to selling them as soon as possible, but it does appear assurances will need to be made before that happens.