Older people living in England’s poorest areas are more likely to be offered inferior social care, according to new figures that reveal a postcode lottery in care services.

A quarter (24%) of the social care services in the 10 most deprived areas in England have been deemed to be inadequate or in need of improvement compared with only 15% of those in the 10 richest areas. It means the proportion of inferior services on offer in the poorest areas is far higher than the national average of 20%.

Councils in these poorest areas, which have suffered the most from cuts in funding from central government, have been hit the hardest and they also have fewer people paying all of their care costs, putting further strain on the services offered.

The figures, based on an analysis by Labour of inspection data compiled by the Care Quality Commission, come at a time when ministers are facing warnings that more services will close as local councils struggle to meet the rising costs of an ageing population after years of public spending cuts.

Last week Age UK said that the provision of homecare services has fallen by three million hours since 2015.

Average spending by councils on social care fell by 13% between 2009 and 2010 and from 2016 to 2017. Over the same period, about 400,000 fewer older people received social care, as the eligibility criteria were tightened by local authorities trying to cope with the costs.

The National Audit Office has already warned that one in 10 councils with social care obligations will have exhausted their reserves within the next three years if the current rate of expenditure continues.

There has also been a dramatic rise in the number of private care providers going out of business. The number entering insolvency rose by 83% in the periods 2016-17 and 2017-18, according to the accountancy firm Moore Stephens. Last year the shortfall in public sector funding for care homes was about £1bn, according to the Competition and Markets Authority.

Councils have already been awarded an additional £150m for social care funding this year, but they have warned that a bigger overhaul is needed. New proposals on the future of social care are due out shortly after ministers promised to publish a plan by the summer.

Delays in dealing with social care were exacerbated during the last election, when the Conservatives were widely criticised for backing a proposal that would have seen the value in someone’s home used to pay for their homecare costs. The plan was soon dubbed a “dementia tax”, with critics calling for a cap on the total costs each person could face.

Now these new figures show that poorer areas are being disproportionately hit by inferior standards of care. In Wokingham, Berkshire, one of the least deprived communities, only 7% of social care services were rated as inadequate or requiring improvement. But in Manchester, a more deprived area, 42% of social care services were rated inadequate or requiring improvement.

Barbara Keeley, the shadow minister for mental health and social care, said: “People in the most deprived areas of the country are bearing the brunt of the Tory social care crisis. It’s time that the Tories ended this postcode lottery of care quality by following Labour’s lead and investing in our social care system.”