Update: Activision has now officially confirmed the existence of Outbreak, which will appear next week when Season 2 begins.

Original story Call Of Duty: Black Ops - Cold War will add a massive new zombie mode called "Outbreak".

References to the long-rumored mode, called "Outbreak," were spotted by several fans on the game's app and website, which teased a (unwatchable) trailer: "Welcome to Outbreak," the blurb reads, "A new, massive zombie experience "; Twitter user Okami noted that the ad remained visible for 30 minutes.

We have contacted Activision about this leak and will update if we hear back.

These ads follow a steady trickle of undead Easter eggs in Call Of Duty: Warzone, including a zombie trial machine that appeared in Verdansk and a disturbing new screen distortion. Some players are also convinced that a freighter off Rebirth Island is carrying Nova 6, the chemical weapon that appeared in Black Ops' first zombie mode.

Whether Outbreak appears in Warzone as is or is simply used as a cross-promotion for Cold War's zombie event, the scale of Call Of Duty's undead challenge is clearly about to grow.Cold War and Warzone's Season 2 kicks off next Thursday (February 25), it seems likely that Outbreak will make an appearance.

Meanwhile, Treyarch is taking to Twitter for a stash of the next Zombies map. There are glimpses of a new map in the Urals and hints of a "massive" infestation that may or may not be related to Outbreak. Warzone, meanwhile, may be preparing to travel to Laos for the next season of Battle Royale.