The Trussell Trust is calling for an inquiry into why the numbers of people turning to it for emergency food has tripled this year.
Over 350,000 people received three days' emergency food from Trussell Trust foodbanks between April and September 2013, triple the numbers helped in the same period last year.
The Christian charity operates hundreds of foodbanks through churches across the UK but estimates as many as a thousand are needed to respond fully to the crisis.
It is alarmed by the rate at which demand has increased over the years. In the period 2008-09, Trussell Trust foodbanks gave emergency food handouts to just 26,000 people nationwide.
The Trussell Trust blames the surge in foodbank usage on rising living costs and stagnant wages.
It has written to David Cameron asking him to look into the causes of UK food poverty.
Chris Mould, Executive Chairman of The Trussell Trust says: "We said in April that the increasing numbers of people turning to foodbanks should be a wake-up call to the nation, but there has been no policy response and the situation is getting worse.
"The level of food poverty in the UK is not acceptable. It's scandalous and it is causing deep distress to thousands of people. The time has come for an official and in depth inquiry into the causes of food poverty and the consequent rise in the usage of foodbanks.
"As a nation we need to accept that something is wrong and that we need to act now to stop UK hunger getting worse."
The situation has become so dire for some people that they are facing a winter of choosing between heating and eating, the charity warned, while some foodbank clients have even taken the drastic step of giving back food that needed cooking because they could not afford to turn on the electricity.
It adds that many people on low-incomes are being impacted by the implementation of April's welfare reforms, with a rise in referrals as a result of the spare room subsidy, sanctioning and confusion caused by the devolution of the Social Fund.
The stark warning comes just a week after the British Red Cross announced that it will provide volunteers for the first time to support Tesco's nationwide food collection for Trussell Trust Foodbanks and FareShare because it is so concerned by levels of UK hunger.
Mr Mould continued: "Problems with welfare are not new, they have existed for years, but the reality is that when welfare provision breaks down, people go hungry.
"We're talking about mums not eating for days because they've been sanctioned for seemingly illogical reasons, or people leaving hospital after a major operation to find that their benefits have been stopped or delayed.
"It's not right that so many more people are now being referred to foodbanks due to problems with welfare, especially as much of this is preventable.
"This is not about pointing fingers, it's about finding solutions. That's why we believe an inquiry is now essential."
Chris Johnes, Oxfam's UK Poverty Programme Director, said welcomed the Trussell Trust's call.
He said: "These figures lay bare the shocking scale of destitution, hardship and hunger in the UK. It is completely unacceptable that in the seventh wealthiest nation on the planet, the number of people turning to foodbanks has tripled.
"Oxfam welcomes The Trussell Trust's call for the Prime Minister to launch an urgent inquiry into why people are forced to turn to foodbanks."