Portia de Rossi Claims Steven Seagal 'Unzipped' During Her Audition

Portia de Rossi claims Steven Seagal put her on the casting couch in his office during an audition -- and she's also blasting her then-agent for a callous and nonchalant reaction.

Portia says the incident happened during her final audition for a part in one of Seagal's movies -- she does not say which one. She alleges the action star told her "how important it was to have chemistry off-screen as he sat me down and unzipped his leather pants."

She says the next bombshell came when she ran out of the office and called her agent. According to Portia's tweet, her female agent only said, "Well, I didn't know if he was your type."

That makes it seem like whenever this happened, it was before 2005 ... when Portia came out. It also hints at premeditation if, in fact, her agent was aware Seagal intended to make the vulgar move.

We've reached out to Seagal's reps.