WWW- It keeps getting messier for “The Insider” host Pat O’Brien.

The celeb chronicler checked into rehab Sunday, just as an embarrassing string of dirty voice-mail messages, which expressed a taste for hookers, cocaine and adventurous (if possibly unhygienic) sex, became public. His reps do not deny that O’Brien made the calls.

Now sources say O’Brien was reprimanded several times for sexual harassment during his time as co-host of rival show “Access Hollywood.”

A witness says O’Brien actually licked co-host Nancy O’Dell’s face at an “Access Hollywood” Christmas party. At the same event, he was seen groping reporter Shaun Robinson’s behind.

A gay male producer told our source O’Brien once said to him, “I have a gift for you.” When asked what, O’Brien allegedly answered, “Bend over.” On another occasion, he allegedly stretched out on the producer’s sofa and asked, “What would you do if I masturbated in front of you?”

He also allegedly offended two African-American employees when he walked into a makeup room and greeted them with, “What’s up, my n–s!” Could it be O’Brien feels that he’s down with the bruthas because he once appeared in a P. Diddy video? O’Brien’s lawyer, Abel Lezcano, said: “As far as being able to verify or deny this stuff, I can’t do it.”

“NBC does not comment on personnel issues regarding our current or former employees,” said a spokeswoman for NBC Universal, which produces “Access Hollywood.” “NBC has a strong policy against harassment in the workplace, and takes corrective action when appropriate.” A rep for “The Insider” declined comment.