TMZ Sports broke the story ... a woman using the alias Jane Doe filed a lawsuit last week claiming Tim Smith -- who suits up in the Kings' Lion costume for events -- was repeatedly inappropriate toward her.

In the suit, Doe claimed Smith hurled lewd jokes her way, made sexually-charged comments and leered at "her breasts and buttocks."

The woman also claims after she complained about Smith -- who manages the team's Ice Crew in addition to playing the mascot role -- he retaliated by firing her from the squad.

Doe says she was eventually able to join back up with the Kings ... but says Smith's action remained inappropriate toward her.

The Kings said in a statement shortly after we published the allegations that they're taking the case seriously ... and have now banned Smith from all team activities until they complete an internal investigation.

"We are aware of the recently-filed lawsuit alleging misconduct by one of our employees," Kings officials said. "The LA Kings take these allegations very seriously and, as an organization, we believe that everyone has the right to work in an environment free from any form of harassment or discrimination."

"We will conduct a thorough investigation into this matter. The employee in question has been suspended, effective immediately, pending the conclusion of that investigation. We are withholding any further comment at this time."