OAPs must have a cast-iron guarantee they will not miss out on fuel payments this winter due to pension credit delays, it was demanded tonight.

Senior Tory Mel Stride issued the warning in a letter to Work and Pensions Secretary Liz Kendall.

The shadow work and pensions secretary’s intervention comes as Labour is facing an ongoing backlash for restricting the winter fuel allowance to only those on pension credit.

Writing in the Daily Express, Mr Stride said: “Ministers claim those who need the winter fuel payment will at least still get it and they will qualify for pension credit. It is their justification for this cruel and poorly thought-through policy.

“But this overlooks the simple fact that many pensioners who would qualify for pension credit, don’t receive it.

“And even for those that apply, it was recently revealed that one in five pension credit applications aren’t even being processed within a 10-week period.

“That means that countless vulnerable pensioners on less than £11,500 a year will miss out on this vital payment in time for the winter.”

The shadow work and pensions secretary repeated his call for the controversial policy to be ditched when Chancellor Rachel Reeves unveils her Budget next Wednesday.

He said: “It is becoming increasingly clear that this policy is not fit for purpose and perhaps all will not be lost – next week’s Budget will be the ideal time to reverse this heartless policy and restore peace of mind to millions of our pensioners.”

In his letter to Ms Kendall, Mr Stride referred to a damning report from the Social Security Advisory Committee (SSAC), which scrutinises the Government’s welfare policies.

The group of experts raised a series of concerns, including that an uptick in pension credit applications would not be processed in a “timely way” despite 450 additional staff being deployed.

Mr Stride said: “Can you guarantee that no pensioner will miss out on their winter fuel payment this winter as a result of their pension credit application not being processed in time?”

The Tory frontbencher questioned the estimated savings of £1.5 billion a year from the policy after the SSAC warned it could be outstripped by a jump in those claiming pension credit.

He urged the Government to commit to carrying out and publishing a full impact assessment into the change after the committee condemned the failure to do so.

Mr Stride also asked if the legislation would be amended following the group’s recommendation that further safeguards were needed for those in receipt of child tax credit and the full rate of housing benefit.

The shadow work and pensions secretary said the report by the SSAC published last week “reveals a shocking litany of oversights and flaws” with the winter fuel payments plan.

He added in his letter: “I have already made clear my strong views on both the substance of this policy and the way the Government has conducted itself.

“SSAC’s conclusions confirm those concerns and raise urgent and significant questions.

“It would be unacceptable for any measure to have been dealt with so quickly and carelessly by a Government – but for a measure of this magnitude, removing vital support from 10 million pensioners including the vast majority of those pensioners already in poverty is quite extraordinary.”

The Department for Work and Pensions (DWP) received around 74,400 pension credit claims in the eight weeks after the Chancellor’s July announcement that winter fuel payments would be limited to older people in receipt of pension credit – up 152% from the eight weeks before.

The latest figures from the last financial year show that one in five pension credit applications were not processed within the 50-working day target timeframe.

The deadline to apply for pension credit to receive the winter fuel payment this year is December 21.

But an “equality analyses” released by the department last month showed that an estimated 780,000 OAPs will lose out on the allowance because they are eligible for pension credit but have not claimed it.

Dennis Reed, director of the Silver Voices campaign group for pensioners, said: “Good on Mel Stride for asking these searching questions.

“Older people will never forget that this major change in policy, affecting 10 million pensioners, has been rushed through without consultation, impact assessment or advance scrutiny.

“Not only are the savings to be made by putting thousands of lives at risk this winter relatively small, but they appear to have been inflated for publicity purposes.

“Furthermore, despite a publicity drive to get more older people onto pension credit, the necessary resources to handle these extra applications appear to have arrived too late.

“And I ask, has the cost of the national advertising campaign been taken into account in the calculation of the savings? What a dreadful mess the Government has got itself into!”

Caroline Abrahams, charity director at Age UK, added: “It’s really worrying if Government delays in processing pension credit claims mean that some older people on low incomes are having to wait weeks and weeks for money that should be theirs, and which they badly need.

“Ministers must pull out the stops to reduce pension credit waiting times and bring in more staff to get through the backlog if that’s what’s required.

“Every day we are hearing about how older people are frightened for the months ahead and plan to ration their heating this winter because they’ve lost their winter fuel payment.

“We encourage any older person who is struggling with their bills to contact Age UK for support.

“We can help them check they are receiving all the benefits they are due, which is important because we know many are missing out on pension credit and other entitlements.”

The Government has blamed a £22 black hole in the public finances left by the Tories, which they have denied.

But the move has come under fire from charities, opposition parties, unions and some Labour MPs.

A Government spokesperson said: “We are committed to supporting pensioners – with millions set to see their state pension rise by up to £1,700 this parliament through our commitment to the triple lock.

“Anyone who makes a successful claim for pension credit and meets the winter fuel payment eligibility criteria will receive their payment, and we are deploying 450 additional staff to process the expected increase in claims

“Over a million pensioners will still receive the winter fuel payment, and our drive to boost pension credit take up has already seen a 152% increase in claims.

“Many others will also benefit from the £150 warm home discount to help with energy bills over winter while our extension of the household support fund will help with the cost of food, heating and bills.”