Around one in four parents knows of a child in their area who may be going hungry, a survey has found.
The poll suggests that the problem may be getting worse, with many parents saying they have seen an increase in the numbers of youngsters they are worried about.
But it also reveals that many are reluctant to get involved, with more than half failing to report their concerns to the authorities.
The survey, conducted by parenting website Netmums and Kids Company, questioned more than 1,100 people to mark the launch of their new Mobiles for Meals campaign. It encourages the public to donate their old mobile phones to feed a hungry British child.
The survey found that a quarter of those questioned said they were aware of children in their area who might be going hungry. Of these, more than one in four (27.8%) said they had seen an increase in youngsters they were concerned about in the last two or three years.
Almost a third (31%) of those who said there was a child they were worried about said they had reported their concerns to someone in authority, such as a school. But 53.2% revealed they had said nothing because they either were not sure enough of their concerns, or did not feel it was their place.
The survey also asked parents who were concerned about a child for the reasons why they thought the youngster may be suffering from "food insecurity".
Around three-fifths said they thought it was because the family did not have enough money to buy the food they needed, while a similar proportion said they thought it was because the family was buying low quality food as they were short of cash.
More than half (55.4%) said that it was because a parent was abusing drugs or alcohol which meant the child was being neglected.
Netmums co-founder Siobhan Freegard said: "This campaign is about mums across the UK taking this unacceptable situation into our own hands. Too many children are not on the breadline, they are way, way under it. It's horrifying to realise how many kids are suffering around the UK. They are having their chances ruined before their lives have barely begun."