With names like Punk IPA, Speed Ball and O8, a new generation of fuller-flavoured ales – part of what has been called the "extreme beer" movement – has been launched in an attempt to push back the boundaries of Britain's national drink.

The new breed of bitters, with their intense flavours and alcohol contents of up to 12 per cent, are the work of young brewing entrepreneurs trying capture the attention – and cash – of lager-guzzling twentysomethings.

Beer writers and aficionados have welcomed the speciality bottles, which can contain 10 times as much hops as a traditional pint, as a necessary revitalisation of a market dominated by corporate giants turning out similar 4 per cent brown bitters.

Download the new Independent Premium app Sharing the full story, not just the headlines

But alcohol campaigners have complained that drinkers may be unaware of the strength of the new products, a single 330ml bottle of which is enough to make an adult exceed their daily recommended alcohol intake.

In January the Portman Group, the alcohol industry watchdog, ruled the brashest exponent of the movement, BrewDog brewery in Aberdeen, had broken its code on responsible marketing for its Speed Ball beer, named after the cocktail of cocaine and heroin which killed the actor John Belushi, star of The Blues Brothers.

Despite the group rejecting complaints against three of BrewDog's other beers, Punk IPA, Rip Tide and Hop Rocker, its managing director, James Watt, accused Portman of being "outdated" and "out of touch". He did, however, concede that his company had been provocative. "We thought we would give them something worth banning us for," he said.

Founded two years ago by Mr Watt and a student friend, BrewDog has expanded rapidly and now produces 2.6 million bottles of beer a year, with alcohol contents of between 4 and 9 per cent, and is selling its 6 per cent Punk IPA in Tesco.

Another of its products, Hardcore IPA, contains 10 times more hops than a standard beer. The result is a drink that scores 150 on a scale of bitterness, compared to 15 for a standard lager. Next month the brewery is likely to attract fresh criticism with the launch of Divine Rebel – at 12.5 per cent beer, its most alcoholic product to date.

Other small regional brewers are also intensifying the strength and flavour of their bottles, although in a less controversial manner. Thornbridge brewery in Derbyshire has won 40 awards for its 5.9 per cent Jaipur pale ale, which uses pungent US hops. The Dark Star Brewery in West Sussex has a 6.5 per cent Six Hop Ale, while Otley in Pontypridd, Wales, makes the boldly marketed 8 per cent O8.

Adam Witherington, drink editor of The Publican newspaper, said: "In the US over the past five years there has been an explosion of craft brewing. Brewers have looked at the way beer is put together and thought, 'How can we do this bigger and crazier?' They're saying, 'Why don't we triple the hops?' Extreme is not so much about ABV, it's about taste and it's about pushing it beyond what beer drinkers are used to."

Alcohol Concern complained that BrewDog appeared to be targeting young people. "The marketing reminds me very much of alcopops," said its chief executive, Don Shenker. "It looks to me like they're going for the 18 to 25-year-old category. They should make prospective customers aware that it's a different type of beer by putting the alcohol units on the label. At 10 per cent, a 330ml bottle would be four units – the recommended daily amount for a man."

BrewDog's head brewer, Martin Dickie, denied encouraging irresponsible drinking, pointing out that some of his bottles cost £4 each. "There's no way someone can drink 20 a night. It's probably the least economic way of buying alcohol. You can get a bottle of vodka for £5."

His products were meant to be enjoyed by friends in their own homes, he added. "You can sit down with two or three friends and open two or three bottles. It's much more relaxed and you are able to savour the beer."