UPDATE: Bin-liner that kept the M1 in Northamptonshire shut for NINE HOURS contained 'highly corrosive material'
The southbound carriageway of the M1 reopened last night after a suspicious object was found between junction 14 and 15.
Thames Valley Police said the object contained a highly corrosive material which had leaked across lanes one and two, which has now been cleared.
There is no evidence to suggest that it was a terrorist-related incident.
A police spokeswoman said: "Thank you to everyone involved for their patience and co-operation."