Firm Dairy Crest said that from Sunday, April 27, it was forced to up the price of its milk by 4p per pint because of packaging, employment and energy costs.

Last year the firm – which has seen its share value drop from 668.63p in April 2007 to just 447.42p this April – raised its prices to cope up with farm production costs, but said this year's rises were to cover the processing, packing and delivery of its milk.

The firm said it had tried to absorb these growing costs, but had reached the point where passing them on to consumers had become inevitable.

Dairy UK, the body which represents milk producers, said it was indicative of sour times across the industry.

Sam Fortescue, communications director, said: 'In common with the rest of the food industry, we've been forced to face growing costs, but we also had quite a poor last winter, and milk production dropped by 300m litres to 13.2bn.

'It was very unsuitable weather from a grazing point of view, which made silage poor, and reduced milk overall in the UK.'

Gwyn Jones, a West Sussex dairy farmer, and National Farmer's Union dairy chairman, said he expected the rises to continue.

He said: 'You can understand why they've had to do it.

'If they are delivering milk, there's the cost of petrol, if they are packaged in plastic, that has gone up, too. They are also having to pay farmers more – after 10 years of depression in the industry, prices have finally risen.

'For farmers, the sale price has gone up about 8p per litre – but remember, the costs for them have also risen by about 6p per litre. So although I wouldn't say by any means they aren't better off than one year ago, it's not by much.'

He said the current rises come against the back drop of decades of falling food prices, with people spending an ever-smaller proportion of their disposable income on food since the 1970s, 'devaluing' it.

He said as more people leave the dairy industry, TB takes its toll on West Country herds, and tighter government regulations come into place, there was every sign consumers would keep paying more for their milk in the coming year.