A jailed gangster claims the case against him is about to collapse because a key informant set up a botched robbery that ended in murder.

In court papers filed last night, reputed Gambino crime-family soldier Anthony Moscatiello cited an online news report alleging that mob rat Howard Santos was the “inside man” on a deadly 2009 home invasion in Queens.

Defense lawyer Joseph DiBenedetto — who’s seeking Moscatiello’s release on bail — wrote that “this undoubtedly deals a crushing blow to the government’s case which is built almost exclusively on an informant who clearly lacks credibility.”

A spokeswoman for the Manhattan U.S. Attorney’s Office didn’t return a request for comment.