Pictures show the back of the truck wedged vertically, apparently in a precarious upright position above the road.

The motorway was shut between Cribbs Causeway and Avonmouth from around 8.40am after the crash.

No injuries were reported, Avon and Somerset Police said.

National Highways said there were delays of at least an hour in both directions.

The agency said: "The M5 in Gloucestershire is closed northbound between J18A (M49) & J17 (Cribbs Causeway) and southbound between J17 & J18 due to a collision whereby a tipper truck has collided with an overhead gantry sign in lane one.

"As a result, all other gantry signs across both carriageways have been affected.

"Emergency services including Avon & Somerset Police are in attendance. National Highways Traffic Officers are also on scene assisting with traffic management."

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Avon and Somerset Police said: "We were called to the M5 at around 8.20am today (Thursday 2 March) following reports of a tipper truck colliding with an overhead gantry on the southbound carriageway between junctions 17 (Cribbs Causeway) and 18 (Avonmouth).

"The motorway is currently closed in both directions.

"There have been no reported injuries."