Junk food has become the modern equivalent of gruel, public health experts have said as they urge the Prime Minister David Cameron to act on the rising numbers of children suffering from hunger and malnutrition.

In the letter published in The Lancet, 170 public health professionals call for the creation of a working group to monitor nutrition and hunger, stating: “The reality is that many hardworking families in the UK are living in poverty and do not have enough income for a decent diet.”

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.

The authors, led by Prof John Ashton, President of the Faculty of Public Health, say 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.

“We have to face an uncomfortable truth: we may be facing a public health emergency in the UK,” said Prof John Ashton. “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.”