Fire crews were forced to return to the scene of the devastating blaze in Fakenham when a hot spot flared up on Tuesday afternoon.
The smouldering flames at the Original Factory Shop site in Upper Market were spotted by a member of the public at around 3.25pm.
David Ashworth, head of operations for the Norfolk Fire and Rescue Service, said: “Following a fire of the nature and magnitude of the Fakenham blaze, it is not uncommon for hot spots to remain.
“In this instance, given the amount of debris that had fallen since the original fire and the fact that crews have not yet been able to get inside the building to make it safe, it was always possible that we might experience a smouldering fire.
“We received a call from a neighbour who reported smoke coming from the building.”