Images have emerged of what appears to be a pre-beta of the first service pack for Windows Vista.

The images, which appear to reference build 6001.16549 seem to be the main pre-beta version, although several other build numbers have been passed on to ZDNet's Microsoft commentator, Mary Jo Foley from testers – something which she suggested could be a move by the company to identify those leaking software.

The arrival of the private beta suggests that the public beta is just around the corner. Microsoft, back in early July had promised that there would be a private beta taking place in mid-july, with the beta version of the service pack being released to the public "shortly thereafter."

The reports come on the same day that Microsoft released the private pre-beta version of Service Pack 3 for Windows XP.