City police officers will now have to think twice before sending out a tweet or posting on Facebook. Police Commissioner Ray Kelly has issued the NYPD’s first rules telling officers what they can and cannot do online.

The order tells officers not to mention or suggest what they do as members of the department.

It also bans them from posting pictures of themselves in uniform, unless the photos are from an official ceremony.

The report warns that social media websites can be used to “undermine the credibility” of officers as members of the department.

Any officer caught breaking the new rules will face disciplinary action and could even be fired.

Last year, 17 officers were disciplined for posting offensive remarks about the West Indian Day Parade on Facebook.

And just this month, two fire department EMTs got in trouble for putting racist comments on Twitter.

One of them was Joseph Cassano, the son of FDNY Commissioner Sal Cassano.

He resigned after the online comments came to light.

(Source: NY1)