NYPD presses cop-steroid ban.

"City cops have been told to stay off the "juice" -- or else.

In an effort to create a stricter steroid ban, the NYPD last week issued a stern warning to its members not to bulk up with supplements purchased online or over the counter.

A bulletin distributed at roll call identified 21 nutritional supplements that contained steroids but failed to list them on their labels.

All dietary supplements are also forbidden, the four-page memo said -- noting that their use would trigger positive drug tests.

The NYPD began random steroid testing in April 2008 after a scandal that tainted as many as 27 cops.

At least four more have been snared by those tests in 2009.

The NYPD noted that illegal steroid use fuels a market run by organized crime."