Officials try in vain to urge calm after government encourages motorists to buy petrol ahead of possible tanker drivers' strike

The effect managed to be both counter-intuitive and almost wearily predictable: the more ministers, police and motoring groups insisted there was no need to panic, the longer and more fractious the fuel queues became.

After sales of petrol were more than 80% higher than usual on Wednesday, queues began forming at some filling stations by 8am on Thursday, just as the roads minister, Mike Penning, appeared on Radio 4 to reiterate the official advice ahead of a possible tanker drivers' strike: if you're driving past a garage then take the opportunity to fill up.

All very well, but as testified by an ever-growing stream of local news reports, tweets and texted photos of snaking lines of cars, not so useful if every driver apparently tries to do so at the same time.

Some of the earlier queues were spotted in Hartlepool, with long lines soon forming at the forecourts operated by Morrisons, Tesco and Asda. Similar scenes were repeated in other locations.

The scale of the problem became apparent at midday when Dorset police announced they had been forced to ask petrol stations to close for a period as queues were causing traffic disruption on adjoining roads.

"The actions of some motorists in queuing irresponsibly at petrol stations is causing danger to other road users," said Chief Inspector Nick Maton. "There is no disruption to the fuel supply in the UK and members of the public should not panic buy." Five petrol stations – four around Bournemouth and one in Weymouth – were shut down until congestion eased.

Soon afterwards another police force, Hampshire, felt obliged to issue a statement pointing out that the Unite union, representing tanker drivers, was still in talks with haulage firms and that a strike was by no means inevitable, let alone imminent.

"There is currently no problem with fuel supplies in Hampshire and therefore we would urge all motorists to continue as normal with their fuel purchases," a spokeswoman said. "Spurious rumours that are being spread online and through other mediums clearly have the potential to engender panic-buying so it is in danger of becoming a self-fulfilling prophecy when there really isn't an issue at this current time."

However, such was the self-fulfilling nature of events that what might have started out as "spurious rumours" on social media soon became well-documented facts, disseminated via the same means. Within a couple of hours a Twitter search for "garage closed" brought dozens of 140 character-long tales of woe from locations including South Wales, Milton Keynes, Taunton, Scarborough and London's North Circular road. Some added notes of disbelief that such seemingly unnecessary panic could spread so quickly. "Nice work, Mr Cameron," added one.

The effects were felt elsewhere in the economy. Even as ministers rescinded the advice of Francis Maude, the cabinet office minister, for motorists to keep "a bit of extra fuel in a jerrycan in the garage" after fire officers expressed alarm, the motor accessories chain Halfords reported a 225% increase in sales of fuel containers.

Official voices weighed in again to urge calm, some blaming the government for the chaos.

The Petrol Retailers Association, which represents around 5,500 garages, said: "This is exactly what we didn't want – people panic-buying. Deliveries are still being made to garages and we are advising people to continue with their normal buying habits."

The president of the AA, Edmund King, said: "We now have self-inflicted shortages due to poor advice about topping up the tank and hoarding in jerrycans. This in turn has led to localised shortages, queues and some profiteering at the pumps.

"Theoretically if 30m cars with half-full tanks are advised to fill up over 24 hours, this means that 750m litres of fuel would be sold, whereas average sales over 24 hours would be 90m litres. Hence the top-up advice means that demand for fuel has increased more than seven-fold. So it is no surprise that the 'top-up' advice has led to shortages."

Assistant Chief Constable Charlie Hall, in charge of industrial disputes for the Association of Chief Police Officers, warned: "We would encourage the owners of filling stations to ensure that their forecourts are orderly and safe. The police may take action where queues are hazardous and pose a danger to the safety of the public."

Yet seemingly little changed, with one garage in Harrogate, North Yorkshire, running dry by 11.30am. Reports from South Wales recounted one village petrol station only selling fuel "to known customers" while some angry drivers reported sudden and mysterious price rises.

As the afternoon went on another, equally predictable phenomenon started to emerge. In mid-afternoon, one woman in Berkshire tweeted: "Seriously idiots stop panic buying petrol, I genuinely need petrol and there is none, just saw an actual fight on the forecourt!"