Cam Jordan -- Cops Open Internal Investigation ... Into Alleged Ass Slap Incident

The Orleans Parish Sheriff's Office has opened an internal investigation into allegations that several deputies at a New Orleans nightclub took NO ACTION when they were told a Saints star had allegedly slapped a woman's ass inside.

The whole situation involved Saints defensive lineman Cam Jordan -- who was accused of slapping a woman's butt and roughing up her boyfriend at Republic nightclub this weekend.

The alleged victims claimed they immediately reported the incident to 3 deputies who were working at the club -- "but the deputies neither investigated the incident nor did they take action."

Now, Sheriff Marlin Gusan has issued a statement saying, "We will be reviewing the actions of the deputies to determine if any policies or procedures were violated."

He adeed, "We will follow all leads in this investigation."