IF YOU'RE an undercover police officer actually working under cover, here's a hot tip: Don't post about your job on the internet with pictures of yourself.

A Washington DC police officer has been outed by a group of activists she had infiltrated after posting about her job on Twitter and Tumblr.

Using an alias, she had become involved in Bangladesh sweatshop protests organised by United Students Against Sweatshop, In These Times reports.

USAS is using the evidence in trying to get an injunction against police officers spying on their activities.

The activists worked out the officer's real identity by piecing together her posts to Twitter, Tumblr, Instagram, Facebook, Wordpress and Yfrog.

In one Tumblr post, she responded to a reader's question about what she wore to work, which appeared to indicate she was a police officer.

"In the position I'm in, it's beneficial to wear ordinary clothes," she wrote. "Plainclothes assignments too, you wear what would blend in."

The posts and profiles have since been deleted.

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