Unum has warned that the Welfare Reform Bill will mean benefits are harder to come by while the Citizen's Advice Bureau (CAB) claims reforms are unfair to the sick.
The CAB fears that cutting contribution based Employment and Support Allowance (ESA) after a year will ‘betray' those who cannot work because of sickness or injury.
And it hit out at plans to double the waiting time for disabled people to become eligible for the new Personal Independence Payment (PIP) once it replaces Disability Living Allowance (DLA).
Gillian Guy, chief executive of the CAB, made the statements in response to the government's unveiling of its new welfare state arrangements.
Guy explained that the Bill heralds the biggest change to the welfare state since it began and supported the principals behind the new Universal Credit, but warned there were still many potential pitfalls for the most vulnerable in society.
"The proposal to cut contribution-based ESA after 12 months will betray people who have worked hard and paid national insurance contributions, only to find that they do not get the support they need if they become sick or disabled before pension age," she said.
"And if the Government is serious about protecting the most vulnerable, people who suddenly become ill or disabled should not have to wait six months - double the current waiting time - before getting the new Personal Independence Payment due to replace Disability Living Allowance.
"The result will be enormous hardship and serious debt for many people at a time when they most need support."
She did however recognise the government's decision to withdrawn proposals to impose a 10% cut in housing benefit on people who have been on Jobseekers Allowance for over a year.
Protection provider Unum highlighted that many people are leaving themselves vulnerable to increasingly stringent welfare claims processes which could be protected against.
It noted that only 10% of people in the UK have insurance to protect their income if they fall ill and yet it is three times more likely to be unable to work for more than a year than they are to die during their working life.
Jack McGarry, chief executive officer at Unum UK, added: "The Government's Welfare Reform Bill will seek to tighten the gateway to benefits for those people unable to work due to sickness or injury.
"Each year, up to one million people in the UK become disabled, and the reforms mean that working people will be able to rely even less on state benefits to maintain the standard of living they were used to prior to their illness."
