The government could breach its self-imposed cap on welfare spending as a result of the cost of the main sickness benefit, leaked documents say.{jcomments on}
Internal government memos seen by the BBC suggest Employment and Support Allowance (ESA) costs are rising and few cost-cutting options are available.
In March MPs agreed a 2015-16 welfare cap of £119.5bn, excluding the state pension and some unemployment benefits.
Ministers have insisted they will not breach the cap. They said they would take measures to ensure welfare spending comes under it. If the limit is breached, ministers will have to explain to Parliament and ask MPs to approve additional spending.
Work and Pensions Select Committee chairman Dame Anne Begg told BBC Radio 4's Today programme that ESA seemed to be doing no better than Incapacity Benefit.
She said: "The big criticism of Incapacity Benefit was that people were put on it and left and nobody reassessed.
"With ESA, there is constant reassessment, but of course that's expensive and that's putting a burden on the health assessors... in order to keep up with the numbers they have to deal with."
The leaked documents say the cost of ESA is projected to rise by nearly £13bn between the current financial year and 2018-19 and is "one of the largest fiscal risks currently facing the government".
The increasing number of claimants, caused by people moving off Jobseeker's Allowance and on to ESA, was cited as a main reason for the rising costs.
BBC’s Michael Buchanan said that, according to those writing the papers, this was because ESA has fewer sanctions than Jobseeker's Allowance.
The documents also say the severity of ESA claimants' illnesses and disabilities has been underestimated, meaning people are staying on the benefit longer than expected.
Read the full story on the BBC News website
