Website GamerLive.TV posted the images ahead of a planned series of announcements by Microsoft later today (March 5).
343 Industries' assistant director of photography Paul Featherstone confirmed their authenticity on NeoGAF, saying they were "100% untouched" and taken with a "debug cam with in-engine depth-of-field".
Halo 4 was unveiled at last summer's E3 in Los Angeles. The game will kick off a new Xbox 360 trilogy, following on from the events of Halo 3.
Extensive details about the sequel were revealed late last year, including the Forerunner-built setting, art direction and story.
Developer 343 Industries has also said that Halo 4 will be more of what made the original Halo amazing.
Halo 4 will be available exclusively on Xbox 360 in late 2012.
Watch Halo 4's announcement trailer below: