Mass protests over rising fuel prices could bring motorways and other major routes to a standstill tomorrow.
Demonstrators are expected to block lanes and take part in ‘slow-downs’ on busy roads across the country.
Police have warned of “serious disruption throughout the day” as the Facebook-organised protest takes place.
Motorways including the M6, M5, M4 and M54 are expected to be hit from morning rush-hour onwards.
The protests, which may also affect petrol stations, are being organised under the banner ‘Fuel Price Stand against Tax’.
‘Slow-downs’ will target two lanes on three-lane motorways and other major routes, campaign group FairFuelUK said.
The organisation is not involved in the action but founder Howard Cox said he is “fully supportive” of the demonstrations.
“I totally support their protest because people have reached the end of their tethers at the moment,” he said.
He said other countries had cut fuel duty by more than the UK and asked: “Why the hell are we not doing it here?”
Protesters are planning to block the Prince of Wales Bridge crossing between England and Wales, according to police.
Gwent Police said it is working with Avon and Somerset Police and neighbouring forces to minimise disruption.
The force warned the protest is expected to take place on the road network between 7am and 7pm on Monday.
Bristol Airport advised travellers to allow extra time for their journeys because of the protest.
It tweeted: “Please note that there is a planned fuel protest to block the River Severn Bridge crossings this Monday July 4 from 8.30am.
“The protest will likely affect the M5, M4 and the two crossings to Wales.
Please allow extra time if travelling to or from the airport.”
The ’Fuel Price Stand against Tax’ Facebook group also announced protests at other locations today (Mon).
They include rolling ‘slow-downs’ on the M6 in Coventry and Cheshire, the M54 in Telford, Shrops.
The protestors are calling for a cut in UK fuel duty to combat rising petrol and diesel costs.
Figures show the average price of a litre of petrol reached a new high of 191.4p on Thursday, while diesel rose to 199.1p.
Chancellor Rishi Sunak is considering calls for a bigger fuel duty cut after a 5p-per-litre reduction in March failed to halt price rises.
Mr Cox called for a cut of at least 20p, and warned there will be a “serious escalation” of protests if it does not happen.