Britain’s biggest food bank charity has called for urgent changes to universal credit after unveiling figures that show it gave out more than 650,000 food parcels in the past six months – a year-on-year increase of 13%.

The Trussell Trust said the government’s insistence on making new claimants wait at least five weeks for their first universal credit payment was driving big increases in the numbers of benefit claimants relying on food banks.

“The only way to stop even more people being forced to food banks this winter will be to pause all new claims to universal credit, until funding is in place to reduce the five-week wait,” said Emma Revie, Trussell’s chief executive.

Play Video 2:03 'Absurd and degrading': how universal credit can ruin lives – video

The trust said more than a fifth of referrals to its network of 428 food banks were generated as a result of claimants facing delays in benefit payments. Nearly a third of this group were waiting specifically for a first universal credit payment.

The biggest single reason for a food bank referral over the period (31%) was the failure of benefit payments to cover the cost of living essentials, while benefit changes – a category that includes benefit sanctions – accounted for 17% of referrals.

Revie said the benefits system was failing to protect claimants from hunger. “Our benefits system is supposed to anchor any of us from being swept into poverty, but if universal credit is to do that, we need to see urgent changes,” she said.

The trust said it gave out 658,000 emergency food parcels between April and the end of September. Of these 233,000 went to families with children. During the year 2017-18 it gave out a record 1.3m food parcels to an estimated 666,000 people.

The Trussell figures come as the UN special investigator on extreme poverty and human rights, Philip Alston, starts his two-week inquiry into the impact of austerity in the UK. He plans to visit a food bank in Newcastle on Wednesday.

The Department for Work and Pensions said it had announced a series of changes to universal credit to ease the impact on claimants. “We will be increasing the amount people can earn on universal credit by £1,000 before their payment begins to be reduced, to ensure work always pays, and introduced £1bn to help people moving over from the old benefits system to universal credit.

“This is on top of the improvements we have already made: advances have increased to 100%, the seven-day waiting period has been removed and we are paying housing benefit for an additional two weeks when people move on to universal credit.”

However, the Trussell Trust said that while the measures announced in the budget last month to help claimants were welcome, they would not solve all the problems with universal credit and they would take between one and three years to come into force.

Margaret Greenwood, the shadow work and pensions secretary, said: “Nobody should be left waiting weeks for a payment, and the government must stop the botched rollout of universal credit now.”

The Trussell Trust figures, which are based on returns from their 428 food banks operating out of more than 1,200 centres around the UK, account for only a fraction of the total number of food parcels given out in the UK. At least 787 non-Trussell food banks exist in the UK, according to the Independent Food Aid Network.