Safety is a major concern in the UK’s NHS Trust, with one in ten hospitals and adult social care providers (13%) lacking in this aspect, the Care Quality Commission (CQC) said in its annual report.
In addition, 6% of primary medical services were also found inadequate for safety and 61% of the hospitals required improvement.
Inadequate safety has occured from various factors, including a failure to properly investigate and learn from incidents and errors, low staff numbers and staffing mix, failure to undertake safety checks and staff not being able to raise concerns.
The regulator warned that pressure to reduce costs could lead to further worsening of the health service in the next few years.
Despite increasingly challenging circumstances, the majority of services across health and social care have been rated as good, with some rated outstanding, implying that most people are receiving safe and effective care.
More than 80% of GP practices were rated either good or outstanding, and in adult social care nearly six out of ten services were rated good or outstanding; 38% of hospitals and trusts, including mental health, have been rated good or outstanding.
CQC CEO David Behan said: "The health and social care sector is facing an unprecedented level of challenge, so it’s encouraging that our findings show that the majority of people are receiving good or outstanding care.
"We have found dedicated staff working hard to treat people with care, compassion and dignity.
"However, we have also found a wide variation in the quality of care people receive.
"Alongside good care we have seen examples of poor and unacceptable care and we rated 7% of care as inadequate.
"A key concern has been the safety of the care, a failure to learn when things go wrong, or not having the right number of staff in place with the right skills.
"Where people are not receiving the quality of care they deserve, we will demand action, and we are now able to demonstrate that half of services have improved following re-inspection."
The study was undertaken under a new tougher inspection regime introduced by CQC last year, which includes inspections of half of the hospitals in the country.
The CQC has not yet completed inspection of all health providers.
Approximately 7% of inspections in 2014/15 resulted in enforcement action from the CQC, compared with 4% the year before.
Behan said: "CQC’s role is to support innovation, share information that can help leaders to better understand the quality of care that their organisation provides and to benchmark against others, and to celebrate great care and great leadership.
"It is also to highlight poor care and poor leadership where we find it, to demand improvement and to take action to ensure that people receive safe, high-quality care."
The CQC is planning to inspect all acute hospitals by the end of March 2016, with community, mental health and ambulance services by next June.
By the end of next September, the CQC intends to inspect all adult social care services and primary care services.