An off-duty police officer was injured after he was struck in the head outside a Midtown East bar early Sunday morning, sources said.

The two men were arguing outside the bar on 2nd Avenue near east 52nd Street at approximately 2:50 a.m. when the officer was hit, sources said.

He was taken to Bellevue Hospital in stable condition, authorities said.

There have been no arrests and a description of the suspect was not available.