Why many top-selling wines are not much more than alcopops dressed up with flavourings and fancy labels

But many would be horrified if they knew the truth about their cut-price shiraz or chardonnay.

Some brands are little better than alcopops dressed up with flavourings and fancy labels, an investigation claims.

What to buy: Stores always have bottles of wine on special offer

Producers use a host of additives to disguise the flavour or inferior grapes without listing them on the labels. In some cases, they are creating so-called 'Frankenstein wines' bulked up with water, sugar and even hydrochloric acid.

In addition, supermarkets stand accused of artificially inflating the price of wine to make discounts seem larger and more attractive.

The inquiry also suggests that only 30 per cent of the champagne sold in this country is worth the high prices demanded by the French producers.

The disturbing findings are reported tonight at 8pm on Channel 4's Dispatches programme, which looks at what goes into the 1.5billion bottles of wine consumed in Britain every year.

Malcolm Gluck, author of The Great Wine Swindle, said: 'Many, many wines are no better than a sort of alcoholic cola. You get artificial yeasts, enzymes, sugar, extracts, tannins, all sorts of things added.'

Many low-end wines have oak chips added to create the impression that they have been fermented in a traditional barrel.

The wine industry has an exemption from food and drink labelling rules which means it does not have to list the additives  -  often used so that vast quantities of wine can all be made to taste the same.

However, some producers go further. More than 60 Beaujolais makers face court this year accused of trying to disguise low-quality grapes with excessive sugar.

This is indicative of a wider problem in France where the Appellation d'Origine Controlee system for guaranteeing quality has been called into question.

A small number of rogues go much further.

Cheers: Consumers are being cheated into paying too much for some wines

For example, some 70million litres of 'Frankenstein wine' was seized in Italy this year.

A mere 20 per cent of the product was wine, while the rest was water, sugar and harmful ingredients such as hydrochloric acid and fertilisers, used to boost the alcohol content and get a higher price.

In some cases chemicals used on the land find their way into the wine.

Tests for the programme found traces of two fungicides in the champagne brands Moet, Veuve Clicquot and Lanson.

The president of the UK's Association of Public Analysts, Alan Richards, said the chemicals were at low, safe levels.

However, 'the public might be very surprised to find traces of them in their champagne'.

Mr Gluck is particularly scathing about champagne.

'My biggest problem is the absurd price of the high-price champagnes which maintain this thin veneer of extraordinary excellence which bears no relation to the liquid in the bottle,' he said.

Master of wine Jancis Robinson tells the programme: 'From my point of view perhaps about 30 per cent of all champagne is worth the money. '

She recently carried out a blind taste test of 80 champagnes.

The popular Piper Heidsieck received the second lowest score, while big-selling brands Moet and Veuve Clicquot came in the bottom 30.

The programme did a blind taste test with 20 people on a £6.99 sparkling wine against Moet, which is three times more expensive.

The testers were equally split.

Miss Robinson is concerned about the industrialisation of wine making.

'Sadly it may be that we will see even more of these techniques of confecting wine, adding the wood chips, even (perish the thought) adding flavouring,' she said.

Britain's Wine and Spirits Trade Association has fought to keep the industry's exemption from labelling rules.

Spokesman John Corbet-Milward said it is possible for drinkers to find out what is in their wine by talking to the maker or importer.

He said the use of different ingredients in varying quantities makes it difficult for producers to come up with an accurate label.