Health experts have warned that junk food has become the modern equivalent of gruel for Britain's poorest children.
Doctors said the 'spectre of Oliver Twist' was now looming over the UK with more families buying cheap processed foods because they could not afford to buy and cook healthy fare for their children.
They have now called on David Cameron to act on the rising numbers of children suffering from hunger and malnutrition.
In a letter published in The Lancet, 170 public health professionals called for the creation of a working group to monitor nutrition and hunger.
The letter states: "The reality is that many hardworking families in the UK are living in poverty and do not have enough income for a decent diet."
The authors, led by Professor John Ashton, President of the Faculty of Public Health, said increasing numbers of poor families are stuck in a 'vicious cycle' of poor diets and poor health, which is fuelling worrying rises in diseases such as obesity and diabetes.
Professor Ashton said: "We have to face an uncomfortable truth: we may be facing a public health emergency in the UK.
"The spectre of Oliver Twist is back. Children are going hungry in the UK: they may not be eating gruel but their parents are having to choosing cheap food that is filling but not nutritious."
The authors, who include Dr Tony Jewell, former chief medical officer of Wales, Dr Adam Bryson, former medical director NHS services Scotland, and Dr Alan Maryon-Davis, Hononary Professor of Public Health at Kings College School of Medicine, say rising food costs are increasing pressures on the poorest families.
The letter says: "During the past five years, food has been one of the three top factors in price inflation, sufficient to worry even higher-income consumers.
"This inflation has translated into families cutting back on fresh fruit and vegetables and buying cheap, sweet, fatty, salty, or processed foods that need little cooking.
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