Last week DWP boss Therese Coffee said that more than 1.2million fresh claims for support had been made since the coronavirus crisis began.
Ministers think up to four million could eventually be lost – putting huge burdens on the welfare bill.
One week nearly six million calls to the Univeral Credit helpline were recorded.
10,000 staff are said to be being redeployed from other areas to help the backlog, and 5,000 more people are being hired.
An insider at HMPO in Glasgow told the Sunday Mirror that some staff were being given a five-day crash course in training to process them that would normally take six weeks.
One said: “I am distraught at the thought of leaving some vulnerable people without anything to live on for possibly weeks at a time when she has very little knowledge of the system.”
The DWP and Home Office have been approached for comment.
A Government Spokesperson said: “Since the start of the pandemic the whole of Government has looked at ways to support priority work.
“Our staff will be fully trained to ensure that they can undertake work on behalf of other government departments effectively so that the most vulnerable in society can access public services as quickly as possible.”
Brits no longer need to call Universal Credit as part of the application process – it can be done online and someone will call back if needed.
The Department for Work and Pension’s (DWP) phone lines struggled to cope leaving people on hold for hours, and it eventually resorted to returning calls where people couldn’t get through.
If you can’t apply online, because you have no interest access or a medical condition or disability that means you can’t use a computer, you can continue to apply by phone on 0800 328 5644 in the first instance.
Claimants are being urged to let the DWP know if they have any changes to their situation online via their journal, too.
Chancellor Rishi Sunak announced that the basic level of Universal Credit would go up by £1000 this year to help people struggling with the coronavirus outbreak.
Brits are currently banned from visiting any jobcentre in a bid to stop the spread of coronavirus.
Benefit reviews and assessments have also been put on hold for three months so staff can instead focus on processing new applications.
Universal Credit and benefit debt repayments have also been paused during the coronavirus crisis, although Universal Credit advances still need to be repaid.
