The Labour leader was asked if he would commit to more support for struggling families after the report, which found that formula milk was being rationed by baby banks to cope with a surge in demand.

Sir Keir said the development was a "terrible story" in the ongoing crisis, which he described as the "single most pressing issue of our time".

He criticised the prime minister for failing to adequately mention the impact that the cost of living crisis has had on households across the UK.

"I'm pretty astonished that in an hour-long address yesterday, the prime minister didn't address the cost of living crisis," Sir Keir told reporters.

"He says that the last 30 years have been a failure and that we need change.

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"He's right about that, but he can't be the change because he's been the nodding dog nodding through the decisions that he now says were part of that failure.

"The change we need is a change from the Tories, not more Tories."

Data from First Steps Nutrition shows average prices of baby formula have risen 24% over the past two years.

The issue has become so severe that there have been calls for a price cap to help families who are struggling to feed their children.

In May, Sky News revealed the desperate measures parents are taking to feed their babies due to the rising costs - including stealing formula or watering down milk or substituting condensed milk for formula.

One mother, 23-year-old Kayla from Swindon, told Sky News "it is literally a milk crisis" as she accused the government of "not listening".

A government spokesperson said: "We recognise the impact that rising prices are having at home, which is why halving inflation is our top priority and why we are providing significant support worth on average £3,300 per household.

"This includes uplifting benefits and delivering direct cash payments, while also delivering a record cash increase to the National Minimum Wage."

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They said the value of Health Start - a programme that entitles women who are 10 weeks pregnant or have a child under four to help to buy healthy food and milk - had risen from £3.10 to £4.25 per week.

"Eligible children aged under one can each receive £8.50 in total per week, a rise from £6.20 a week," they added.

In his conference speech, Mr Sunak made reference to the rising cost of living in the context of his desire to halve inflation.

Liberal Democrat deputy leader Daisy Cooper also criticised the prime minister's conference speech, saying he had "nothing new to say on the big issues facing families, from the cost of living crisis to local health services that have been run into the ground".