The rapid rise comes amid wider concerns about the sustainability of Scotland’s public finances. Figures last week showed Scotland’s public spending deficit rose to £22.7bn last year amid dwindling North Sea oil revenue.
Finance Secretary Shona Robison last week announced “emergency control measures”, effectively blocking any spending on non-legally obligated activities this financial year.
Mr Phillips said many of the issues facing Scotland were not “one-off pressures”.
He said: “The trade-offs it faces now between tax rises, spending on its more generous social security system and public services are going to become more acute.”
He added: “If it continues with its social security policy and was to prioritise healthcare, that would mean having to make big cuts to other areas of spending.”
The Scottish government spent £20,418 per person on services, benefits and other public spending last year, compared to £18,001 across the UK as a whole. This gap is now at a record level.
A spokesman for Social Security Scotland said: “There has been an increase in applications for disability benefits across the UK, including for Adult Disability Payment in Scotland.
“We designed this payment in consultation with disabled people and are delivering a service based on dignity, fairness and respect for all. We are committed to ensuring disabled people get the financial support they are entitled to.”
The spike in disability benefit claims comes as Scotland grapples with long-standing challenges around worklessness and ill health. Some 23.1pc of the Scottish population is economically inactive, compared with 22.2pc across the UK as a whole.
Hannah Randolph from the Fraser of Allander Institute said the higher rate of inactivity was intrinsically linked to ill health, posing challenges for public finances.
She said: “If you have higher inactivity with fewer people working, then you have a smaller tax base. That combines with greater pressures on the health system, which is then more costly. So you have a crunch from both sides.”
Mental and behavioural disorders were the most common reason for receiving adult disability payment, according to Social Security Scotland, with 38pc of claimants citing it as their primary problem.