UPDATE: According to Popeater's Rob Shuter, Joan believes without a shadow of a doubt that "FOX canned her over her Palin comments."

He continues: "Asked whether she'll accept an invitation to come back to 'FOX & Friends,' Joan went hardcore, saying they can 'go f**k themselves.'"

EARLIER: After commenting to a TMZ reporter that Sarah Palin "should go someplace, like to another planet," and also that she "is stupid and a threat," Joan Rivers was supposedly banned from appearing on FOX & Friends.

On Rivers' Twitter account, the 77-year old comedian writes in three successive tweets:

"While @melrivers and I were promoting our new @wetv reality show, I made a joke about Sarah Palin that was picked up by @TMZ. As a result, our appearance on the Fox News Channel tomorrow morning has been cancelled. Outcome: DON'T PISS OFF SARAH PALIN. She’s apparently 'very powerful,' and is obviously still smarting from the end of her reality show."

In true Rivers style, she finishes off in a final summary tweet: "I was cancelled from Fox for saying Palin is 'stupid and a threat'. Wait till I REALLY shock them with Aretha Franklin is a bit chubby!"

Apparently the whole thing was a scheduling mixup, at least that's FOX & Friends producer Lauren Petterson told the Wrap.

“Due to the volume of news topics tomorrow morning and a full show, our booker mistakenly canceled Joan’s appearance...Our booker mistakenly canceled Joan’s appearance instead of re-scheduling her for Friday’s show," Petterson said.

Is it possible to "accidentally" cancel a big name like Joan Rivers? Still no word from Fox or Rivers' publicist about accepting a new booking.