As spotted by Digital Spy forum members, a placeholder has appeared on Freeview channel 304 confirming the change.
In a blog post in April, the BBC's Olympics chief Roger Mosey said that the channel will run a simulcast of the Red Button Olympic live streams in "glorious HD".
The initiative is possible due to the still-available capacity for the fifth HD channel on Freeview, following Channel 5's decision not to bid for the slot.
The BBC is currently evaluating bids from content providers and broadcasters wishing to take the valuable HD channel, after confirming that it has "no need" for the capacity in the long term.
While that process goes ahead, the corporation will use the capacity to bring more HD coverage of the Olympics to viewers of digital terrestrial television (Freeview).
Mosey said that capacity limitations mean that it will not be able to deliver all 24 HD live streams to Freeview audiences through their TVs, as will be available on satellite and cable.
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However, the temporary extra channel will mean that the number of HD services covering Olympic events on Freeview will expand to three, alongside BBC One HD and BBC HD.
"It's worth noting that the Freeview Red Button service will be picking the best of the action from the sports not being covered on BBC One and BBC Three, so we'll deliver more top-quality Olympic action from a range of venues in subscription-free HD," said Mosey.
Freeview HD viewers will be able to access the additional temporary high definition service directly via the Red Button on BBC One HD and BBC HD.
But the coverage will also be listed on the Freeview HD EPG at position 304, alongside the other BBC Red Button services on 301 and 302.
Using the broadcast capacity means that viewers with Freeview personal video recorders will be able to record selected BBC Olympics coverage in high definition.