Traffic Scotland reported the spill and the breakdown at 6am on Monday and issued an update just after 11am confirming the road was still closed.
A Police Scotland spokesperson said officers were called at 4.10am to assist with traffic management after an HGV broke down on the northbound A1 near Ayton.
A second HGV reported an oil spill at 4.55am near Lamberton and as a result the southbound carriageway was also closed.
Drivers are advised to plan ahead and use alternative routes if possible to avoid delays.
Two 13-mile diversions are in place for drivers who do approach the closure.
People travelling south are being diverted right towards Ayton – just south of the A1107 junction – and will rejoin the A1 at the north end of the Berwick bypass.
While drivers going north should take a left on the A6105 – at the north end of the Berwick bypass – before rejoining the A1 at the south exit from Ayton.
Police Scotland remain on the scene working with Northumbria Police and the road will be closed until further notice.
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