Some 26,000 sufferers receiving benefits face financial difficulty and worry if they are forced to move to the new all-in-one benefit system before problems with payments are solved, Macmillan Cancer Support said.

From 2019, people too ill to work and currently receiving Employment Support Allowance (ESA) are due to move to the new system, which has faced widespread criticism.

One terminally ill patient branded the new system "a complete nightmare".

Angela Raine, a 55-year-old grandmother from Stanley, County Durham, who has incurable breast cancer, had to give up her job in a pharmacy after 13 years when she was diagnosed in 2017.

She said: "I can't explain quite how stressful it is - I want to cry just thinking about it.

"I was trying to cope with being told I may die and yet at the same time I'm having to fight to just get a little money, so that we can survive.

"Navigating the system is a nightmare, that's quite honestly the only way I can describe it.

"The forms are all so confusing and difficult. It's as if they do that to stop you from applying."

MP for North Durham, Kevan Jones, said: “Despite all the evidence of the serious difficulties that people are facing when making a new claim, the Government is pushing ahead with its plan for managed migration. Ministers need to listen to people like Angela and come up with a credible plan to fix Universal Credit’s many failings before more people suffer.”

Macmillan hit out at UC saying that under current rules cancer patients, 28 per cent of whom have no savings, face a five-week wait for cash after they move across.

The National Audit Office also found around 67% of people with health conditions or disabilities did not receive their first Universal Credit payment on time.

As a result, cancer costs an average of £570 a month for the majority - some 83 per cent of patients - due to lost income and extra outgoings, such as increased household bills due to feeling the cold more.

The charity said any delays or obstacles to receiving financial support can be a source of extreme worry and financial hardship at an already difficult time.

Applying online can create stress, especially if sufferers are in hospital or have poor computer skills.

Having to visit jobcentres to complete applications also leaves them at risk of infection during treatment, it warned.

Changes to the consent process also make it more difficult for advice services, like Macmillan’s Benefit Advisors, to support people with their claim which can make the process even harder.

The charity said it has had more than 26,500 calls about benefits this year, including 215 in the last month about UC.

The charity's chief executive Lynda Thomas said: "People with cancer should be able to focus their energy on their health, not worrying about how to make ends meet when they are too unwell to work.

"It is unacceptable to force patients to risk infection at jobcentres, log on to computers from hospital and wait more than a month for vital financial support, even at the end of their lives.

"The system is failing people with cancer and we urge the Government to fix this benefit, before tens of thousands more vulnerable people are put at risk of hardship."

UC replaces six existing benefits - ESA, Income Support, income-based Jobseeker's Allowance, Housing Benefit, Working Tax Credit and Child Tax Credit - with a single payment.

The rollout started with new recipients in pilot areas in 2013, but from July 2019, around two million people already receiving the old benefits will be moved on to UC, in a "managed migration" which is not due for completion until 2023.

The system has been heavily criticised by MPs amid calls for it to be halted to allow changes to be made. Work and Pensions Secretary Esther McVey has previously said the rollout would continue, but she would ensure the Government "get it right".

• For free support call 0808-8080000 or visit macmillan.org.uk