More than half of adults in the UK are struggling to afford to drink in pubs, according to the Campaign for Real Ale (Camra).

The average price of a pint of beer in London is now £5.20 and regularly tops £6. Across the country, the average is about £3.50, leading to many drinkers staying at home with cans of beer bought in supermarkets instead, said Camra, which warned that more than a dozen pubs a week were closing as a result.

It said its research found that 56% of drinkers believe the price of a pint of beer in a pub in the UK has become unaffordable.

Prices have risen steeply in recent years, with various taxes including beer duty, business rates and VAT accounting for a third of the cost, said Camra.

The most expensive places for a pint outside London are Oxford (£4.57), Edinburgh and Bristol (£4.35), and Brighton (£4.24). The cheapest is Carlisle £2.35, which is two-thirds of the UK average.

Craft beer in supermarkets costs about £1.50 per bottle or can (330ml) and while mass-produced lager and bitters averages less than £1.

Camra is concerned that the government is planning to increase the tax paid by pubs in the November budget. Beer duty is to rise by about 2p per pint under Treasury plans, and small pubs are to lose the £1,000 in business rate relief introduced in 2017, but scheduled to end in 2019.

The campaign group warned in May about the scale of pub closures, predominately in the south-east. The industry has campaigned for a VAT reduction to allow it to compete with retailers.

Chains such as Wetherspoons have bucked this trend by using significant buying power to keep customer prices low. For tied and small independent pubs, that is not an option, say campaigners.

Camra’s national chairman, Jackie Parker, said: “It’s no surprise that most people are finding pub pints unaffordable, given the tax burden they’re facing. Beer drinkers will naturally look to more cost-effective ways to enjoy a drink, such as buying from off-licences and supermarkets for home consumption.

“The result is incredibly detrimental to our local communities and to our own personal connectivity. Having a good local makes people happier, better-connected and more trusting. Furthermore, pubs help bring communities together and support the local economy. The reality is that there are very few places that can replicate the benefit provided by our nation’s pubs, and once they’re gone, they’re gone for ever.”