Soaring numbers of blocked beds continue to disrupt the NHS in England - despite figures suggesting it may be starting to recover after a challenging start to the year.
Delayed transfers of care - when patients are fit to leave hospital but services such as nursing at home are not in place to look after them - caused 167,677 days' worth of hold-ups in April, the second highest on record.
This was only slightly less than the record number of 169,928 the previous month, according to new figures from NHS England.
It was also revealed that nine out of 10 patients at major A&E departments were seen within the target of four hours in April following record levels of emergency admissions the previous month, when more than two million people attended.
Demand on frontline services eased in April, allowing departments to hit 90% for the first time this year, up from 87.3% in March but still five percentage points short of the national target.
Matthew Swindells, NHS England's national director of commissioning operations and information, said: "April's figures show frontline services beginning to recover from a challenging winter and a late spike in flu, with A&E performance nearly 3% higher this month.
"However, these new figures also show social care-related delayed hospital discharges up by 37% compared with last year - further proof that increasing pressures in social care are spilling over into the NHS. Services were also affected in April by two 48-hour periods of industrial action."
Hospitals handled more than 1.8 million A&E attendances in April, and there were 460,000 emergency admissions - a 2.2% increase from the same month last year.
A total of 655,377 days have been lost to "bed blockers" so far in 2016. Over the same period in 2015 the number was 563,165.
A snapshot figure, measuring the number of patients delayed at midnight on the last Thursday of the month, was the highest since current records began in 2010: a total of 5,924.
An NHS England spokesman said: "It's important patients who are well enough to leave hospital can do so at the earliest opportunity, and in some parts of the country the system is working well. However, performance varies and growing pressure on social care will intensify delayed discharges and put extra pressure on hospitals in the future.
"These figures underline the importance of joined-up care within the NHS and the dependence of hospitals on well-functioning social care services - particularly for older people living at home."
Charities blamed a gap in social care funding on the high number of people being kept in hospital unnecessarily.
Janet Morrison, chief executive of Independent Age, said it was "abundantly clear that chronic under-investment in social care" was sending numbers rocketing, while Vicky McDermott, chairwoman of the Care and Support Alliance, said the funding crisis was heaping "needless pressure" on to the NHS.
Saffron Cordery, director of policy and strategy at NHS Providers, said: "In the middle of the longest and deepest financial squeeze in the NHS's history it is easy to see why the majority of NHS providers are not hitting demanding targets. Correcting this will be a major challenge.
"Whilst some pretend that this is a result of poor NHS leadership, too many organisations are being affected for this to be the case.
"The problems are the result of demands being placed on NHS organisations that are impossible to deliver with the money available."