The United States Federal Bureau of Investigation is advertising for automated computer softwares that will monitor people's posts on social networking sites, including Facebook and Twitter.

The FBI's Strategic Information and Operations Center (SOIC) posted a tender for a "Social Media Application" on FedBizOpps.gov web on January 19.

The advertisement says the application will collect "open source" information and should be capable of sniffing through online media sites like news and social networking sites for keywords to help improve its real-time intelligence when it comes to current and emerging security threats.

Sources said some US government institutions have already used similar software to collect "open source" information, a practice that have been kept out of the knowledge of the public.

It is believed to be the first time the US government has admitted it will apply advanced technologies to monitor the public media.

The US media reported the police made it public because that it's much easier to find a PHD on researching quantification in Silicon Valley than from the governments

The app will search for keywords searches which will be displayed in real time as different levels of threats on maps, possibly using colors coding to distinguish priority with the ability to immediately translate foreign language tweets into English.

The FBI says the information would be used to help predict the likely actions of "bad actors", detect instances of people deliberately misleading law enforcement officers and spot the vulnerabilities of suspect groups.

The software may continuously record the data for a follow-up investigation by police and signal the threat levels by different colors, for example red for terrorist attacks and yellow for theft.

The police also hope to predict developing trends or monitor the next step of subversives though research, investigation, trend analysis, mode matching, clue connection and time axis analysis.

Though the police refused to comment on the software's prediction analysis, the idea is feasible as Facebook and researchers in some academic institutes have successfully deduced a lot of information about users, such as the names of users' friends who are not even mentioned on the social network, and users' location, which are not disclosed on the social network.

However, this technology is not mature. A former staff member with the US Ministry of Defense said there are softwares that help users know more about someone else by analyzing their recorded information, including the kind of books they like and the places they like to go for a meal. Then the software utilizes such information to deliver personalized advertisements. It doesn't matter much if the software mistakenly recommends books the users dislike, but it will be a big problem if a normal person is falsely classified as a terrorist to the police.

Even if the police have underlined that they will only monitor "public information " and cannot get access to private message on Facebook and Twitter, but the government's move is not welcomed by the public, said an advocator from Electronic Frontier Foundation, a non-profit, non-partisan organization in San Francisco working to protect fundamental civil liberties.

One thing worth mentioning is that most users are actually using "public information" to communicate with their friends and relatives while they believe all the messages or threads they posted can only be seen by a close circle, giving them a "safety sense" of free expression.

The software will save this kind of "public information" for a long time, creating potential privacy concerns. A spokesman from London-based Privacy International told BBC that the police's move of bringing numerous users into surveillance shows its opposed stance against the public in terms of privacy issue.

The police claim that surveillance of Internet is aimed to better ensure national security. To catch a terrorist plotting to bomb a soccer field is naturally a good thing, but some media think such a move goes against the principle of protecting privacy and freedom of speech. The core is how to identify terrorists. Are they hackers from Anonymous, supporters of Wikileaks, protestors in the Occupy Wall Street movement or anyone at large?

Some reports said although the police can set some key words to monitor possible terrorism or catastrophic events, the possibility can not be ruled out that the police may use particular key words to monitor the public and then make further speculation even if it is untrue.

Some media have also suggested the police have become tired of monitoring Facebook and Twitter manually and want to reconstruct the monitoring program. In the near future, anyone's messages or posts can be tagged as red on a police digital map and seen as subversive.

"If each word you say is under watch, are you still going to utter whatever you would like to? If you realize that a simple joke will send you to jail, dare you say anything again?", said an anonymous internet users.