Police issued a warning to motorists that a “slow-moving rolling roadblock” was causing delays on the M4 and M5 highways near the border of England and Wales.
The Prince of Wales Bridge, which connects southern Wales and England, also experienced “significant delays” in both directions, according to the police.
Motorists were advised to expect delays and to rethink their trips because protesters were moving at a speed between 25 and 30 mph.
Similar protests and delays were also reported elsewhere, including on the M180 in Lincolnshire. West Yorkshire Police, meanwhile, claimed to be in “negotiation with a small group of fuel price protesters” at a motorway service station, though they reported no disruptions during morning rush hour.
The demonstrations are the most obvious response to the rising cost of fuel, which is aggravating the cost of living crisis for many drivers.
Although they appeared to be organizing the protests on social media, the demonstrators did not appear to be working as a single campaign group.
On Monday morning, the “Fuel Price Stand Against Tax” Facebook group, which was started in March, had almost 50,000 members, and 140,000 people had signed an online petition calling for the fuel tax to be reduced by at least 30%.
Chancellor Rishi Sunak reduced fuel duty by 5p per litre in March, but the rise in the price of oil has had little of an effect.
Following government concerns about whether the reduction in fuel duty was being passed on to drivers, the UK competition watchdog also opened an investigation into the competition in the retail fuel market.
The average cost of filling up a family car with gasoline hit £100 for the first time last month, up from £71 the year before, according to the RAC. Fuel prices have been breaking records on a daily basis.
According to the motoring group, a litre of unleaded gasoline cost £1.91 on average on Monday morning, while a litre of diesel cost just under £2.
The cost of raw materials and taxes are included in wholesale prices, which have increased by about 50% this year. Retailer costs, such as delivery, are not included.
The disruption on UK roads on Monday was the most recent in a year, when the government passed new legislation to stop what it called “guerrilla protests” after climate change demonstrators repeatedly halted traffic on congested highways.