A man posing as a convincing cab fare quickly revealed himself to be an armed robber on multiple occasions, police say.

The NYPD has received five reports between Sept. 18 and 25 about the suspect. The head of the New York State Federation of Taxi Drivers says the man struck once more on Sept. 24, but the driver in that incident did not report it to authorities.

Polices say the suspect has driven away in four livery cabs after threatening drivers with a knife or gun.

The taxi federation is offering a $1,000 reward for any information about the suspect.

Union leaders advise drivers in the borough to make sure their cameras are working before hitting the road and urge them not to pick up illegal street hails.