Popular NYC Restaurant SUED -- You Let Celebs SMOKE WEED In the Basement!

One of the hottest restaurants in NYC has a hidden room where stars secretly get BAKED OUT OF THEIR MINDS ... while eating delicious Chinese food ... this according to a new lawsuit obtained by TMZ.

The restaurant at the center of the controversy is Philippe Restaurant in Midtown ... which feeds expensive Asian cuisine to stars from the likes of Rihanna to Woody Allen.

But according to a new lawsuit filed by 4 employees, the guys who run the joint frequently give permission to some of their famous clients to smoke herb in a private basement dining area.

The employees don't name the celebrity pot-smokers -- but do note that rappers Rick Ross and Nicki Minaj have dined in the basement.

In the suit, the employees claim they were forced to serve the stoner clientele ... "which exposed them to smoke from a harmful and illegal substance."

One employee claims he was fired after complaining to management about not being able to breathe while working in the basement and smelling like pot when he returned home from his shift to his wife and son.

The other employees claim their shifts were significantly reduced in retaliation after they joined another lawsuit against the restaurant in which they claim they were unfairly tipped out and denied overtime.

All 4 employees are seeking unspecified damages.