If an at fault accident claim has been filed but no police report was made is this recorded anywhere that can be accessed by other insurance companies?

Yes, this is accessible to most Insurers thru your Auto Plus or MV Search records. Now keep in mind, dependant upon the CAUSE of the accident being considered an At Fault, there usually MUST be a police report involved for the insurance company to determine fault against you. (unless you actually were telling the insurer the detais eg)you slid on ice and hit a car)