IT has been one of the biggest changes in our drinking culture in a generation, with 200 new microbreweries opening UK-wide in the past year alone.

But now industry experts have warned the craft beer sector is under threat as global brewing giants attempt to muscle in to the sector.

The Campaign for Real Ale (CAMRA) has said that the world’s two biggest brewers, AB InBev and SABMiller, which are due to merge this month at a cost of £79 billion, have already moved into the London craft sector.

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In the newly published edition of the Good Beer Guide, the organisation has said that major brewers can strip costs from production due to their ability to bulk buy raw materials like grain and hops at enormous discounts, with cheaper beer that drives craft products off bars and supermarket shelves.

Last week it was reported how the Scottish arm of North American brewer Molson Coors said it was open to making acquisitions in the country’s craft beer sector, having snapped up Cornwall-based Sharp’s in 2011 and Cork’s Franciscan Well in 2013.

Good Beer Guide editor Roger Protz said: “The way in which the global brewers are muscling in on the craft sector in Britain and other countries is a cause for concern and a potential threat to the independent sector.

"In its 44 year history, the Guide has never been complacent and believes that beer drinkers’ choice and freedom demand constant vigilance.”

But in Scotland, where craft beer still only accounts for a small proportion of overall beer sales despite a rapid growth, industry leaders were less pessimistic.

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Chris Miller, currently commercial director of export group Craft Beer Clan of Scotland, recently warned of the need for investment to keep up with rapid sales growth but said the Camra claims were "not a million miles off the mark".

Mr Miller, the man widely known for growing Harviestoun into one of Scotland’s leading craft beer producers, added that future mergers and acquisitions in the sector were inevitable.

But he added: "If (the big brewing companies) choose to flex their muscle they probably could. But the consumer understands why that would be and are willing to pay that little bit more. We all claim our palettes are becoming more sophisticated."

Scott Williams, founder and brewmaster of Williams Brothers Brewing Co, said: "It is obviously true that the big players do take cost out of brands they buy. Inevitably this makes the liquids less flavoursome causing consumers to search for a better alternative.

"By giving 'craft' beers more exposure it draws more attention to the world of small craft brewers which helps to expand the market.

"There will come a time when this will be to the detriment of the small brewers but that is a way off yet. Quality driven consumers are hard to fool and are growing in number - so long as brewers are creating recipes and not accountants all will be good."

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Recently, SABMiller bought the Meantime Brewery in Greenwich, paying £120 million but then selling it to Asahi of Japan due to the demands of regulators in the United States and the European Union.

AB has also bought another London craft brewery, Camden Town, for £85m, pushing it as a leading player in the UK capital’s beer sector amid claims it will use its marketing muscle to undercut competitors.

But Mr Protz added: “The real ale revolution goes roaring on. As well as new breweries opening, others are expanding their sites or moving to bigger premises to cope with the demand for their beers.

“In an overall declining beer market, real ale’s share is impressive. It’s not only in growth but is expected to grow dramatically over the next few years.”