Pubs are closing down at a high rate because a pint at the bar is becoming an “unaffordable luxury”, according to a survey by the Campaign for Real Ale.

Figures released by Camra show that 21 British pubs every week are calling last orders for good, as customers balk at prices.

The average cost of a pint of draught bitter has risen from £1.78 in 2000 to £2.99, according to Camra, which has 180,000 members. At the same time, supermarkets have boosted their revenues by luring shoppers with bulk-buy offers on beer, wine and spirits.

A survey commissioned by Camra found that 82% of Britons put the rapid rate of pub closures down to the fact that beer bought in supermarkets to drink at home was significantly cheaper. Nearly 78% placed some blame on the high rents and wholesale beer prices charged by property companies to pub landlords renting premises from them.

And 69% of the 2,000 people surveyed for Camra by YouGov blamed the dwindling number of pubs on taxes such as beer duty, VAT and business rates.

Although the rate of closures has slowed from 27 to 21 a week since Camra’s last update in February, its chairman, Colin Valentine, said the number was still “alarming and unacceptably high”.

Camra has campaigned to reduce taxes such as the beer duty escalator and has enjoyed some success in efforts to secure a fairer deal for publicans from the property companies who own their pubs. But Valentine said that the cost of beer was still scaring off customers despite the best efforts of Camra and other campaigners.

“A pint in a local is becoming an unaffordable luxury, driving people away from the safe and social environment of the pub and encouraging them instead to drink cheap alcohol in their homes,” said Valentine. “We’d urge the government to continue to work to address what people see as the key issues threatening pubs.”

Camra said the total number of pubs in Britain had declined from 52,750 in December last year to 52,201 in June, or approximately one for every 1,227 people in the country.

Valentine urged beer lovers not to be dissuaded by high prices, asking them to “support their local pubs as much as possible” by signing up to local campaigns to save those under threat.

The decline of pubs has been accompanied by an explosion in microbreweries making more upmarket craft beers that are available in off licences – some have even opened taprooms for walk-in customers. Demand for prime property has exacerbated the fall in pub numbers as companies buy or redevelop them to turn into lucrative housing projects.

Camra’s warning about the malaise in the British pubs industry comes as the Great British Beer Festival takes place at London’s Olympia venue. The real ale group is making a concession to drinkers’ varying tastes by making more cider and perry available at the festival.

Two bars are devoted to the beverages, with Camra saying that “demand for both traditional drinks continues to grow within the beer festival community”. But it upheld its reputation for purism, saying it was only advocating “real cider”, as opposed to mass-market bottled options.

A survey carried out for Camra by YouGov found that 60% of the people polled drank cider on a night out in a pub, while 41% knew the difference between “real” cider and other ciders.