The number of patients on hospital wards in England has been at unsafe levels at nine in 10 NHS trusts this winter, BBC analysis shows.
To minimise the risk of infections and delays in getting treatment, hospitals are meant to have no more than 85% of beds occupied.
But the analysis showed 137 out of 152 hospital trusts have been above that level since the start of December.
NHS bosses said hospitals had major problems discharging frail patients.
They said a lack of care in the community meant they were having to keep patients on wards.
A poll by Ipsos MORI for the BBC has suggested three-quarters of those surveyed in the UK want to see charges increased for people coming from abroad as a way of raising more money for the NHS.