Update: Nintendo has told GameSpot that the reports are not true, and it will not be showing off any new hardware at E3 2014.
Citing a "third-party publishing source" that also claims new games will accompany the hardware, and be playable at the show, VideoGamer then suggests that the hardware reveal will be a successor to the Wii U.
Peer Schneider at IGN has also suggested Nintendo has some new hardware up its sleeve. "I've heard it from multiple people now," he said on a recent Nintendo Voice Chat podcast. "I've heard it from someone who used to be at Nintendo, I've heard it from somebody on the third-party front."
Schneider, however, notes that hardware is a broad term that could mean anything from a simple peripheral to a new Nintendo console.
MCV, too, says it's heard that Nintendo has new hardware to unveil but, like Schneider, is not yet certain what it could be.
Nintendo, meanwhile, said it does not comment on rumour or speculation. The company will release all its E3 announcements at 09:00 PT on Tuesday, June 10.