The building has been left almost completely destroyed following an enormous fire, which started at around 10.30pm on Wednesday (December 14) and raged through the night.
It was finally brought under control at around 2.30am on Thursday but was still burning.
The interior of the southbound services has been gutted.
A Welcome Break spokesman said on Friday (December 16) that the southbound services will definitely be closed in its entirety until early January.
“Welcome Break will be building a temporary structure with the aim of trading some of the services from January onwards, but there is no specific date for this,” he added.
The spokesman also confirmed that the bridge linking the southbound and northbound service areas, renamed the Scott Mills Bridge after the BBC Radio 1 presenter , remains closed 'until further notice'.
One eyewitness claimed the fire started in KFC when a machine exploded.
A KFC spokesperson said: “The source of the fire is not yet known, but we understand Welcome Break are assisting the fire services with their investigations.”