Updated with CBS (NYSE: CBS) response below: Back in February, US TechCrunch co-editor Erick Schonfeld’s story that Last.fm handed member data to the litigous Recording Industry Association of America drew a fierce denial and this response from the social music site: “TechCrunch is full of shit”. Now Michael Arrington himself, clearly stung, is having another go - and it’s getting even uglier…

SEE ALSO: CBS, Last.fm Deny Passing User Data To RIAA; Some Users Delete Accounts

Arrington says his site’s original source, employed at Last.fm parent CBS, has been sacked for the original leak, while a second source “very close to Last.fm” says it was CBS and not the music site that handed the data. The implication is that CBS misled Last.fm in to giving data for internal use that was then passed up to the record business association. “We believe CBS lied to us,” Arrington writes.

Again, it’s resulted in one or two accounts being deleted, but co-founder and CTO Richard Jones Last.fm architect Russ Garrett is reprising the “full of shit” line in a forum post: “That particular data is controlled tightly inside Last.fm ... any request for such data would have to be approved by myself first. The suggestion that CBS’ ops team provided this data is just not possible - Last.fm operates as a separate entity and their operations staff do not have access to our system ... It really seems like someone is trying to slander us here.” It hasn’t stopped there, however - the whole, sordid episode is playing out in a playground Twitter argument between Arrington and co-founder Richard Jones, too; read it after the jump.

CBS responds: Meanwhile, CBS, once again, is trying to shake this story. The formal statement from CBS Interactive: “Both CBS and the RIAA have already stated quite clearly, for the record, that absolutely no individual user or listener information was supplied to the RIAA by last.fm or any division of CBS Corporation in the past, nor do we plan to do so in the future. The story posted by the website was based on an unnamed tipster. No inquiry was made to CBS or last.fm about the veracity of the anonymous source. Those who consult such blogs should be aware of the standard by which such postings are sourced and published.”