Barnsley Hospital is being investigated by health watchdog Monitor following concerns over its finances and long waits for patients in A&E.
The trust has breached the national A&E quarterly target - which says 95 per cent of emergency patients should be seen within four hours - five times within an 18 month period.
Its finances have also deteriorated - in February the trust was in the red to the tune of £2.3m.
Frances Shattock, Monitor’s regional director for the north, said: “We are opening this investigation because we want to understand why the trust is facing problems in its A&E and with its finances so that we can help it to improve and provide a good quality service for local people.
“We expect the trust to take rapid action to address its problems whilst an investigation is ongoing. If necessary, we will not hesitate to take regulatory action.”
A spokesman for Barnsley Hospital NHS Foundation Trust said: “On March 31 the trust declared a serious incident into financial irregularities at the hospital. Supporting this, the trust has also commenced both internal and external investigations into our how our finances have been managed.
“Monitor has announced that it will be carrying out its own investigation into the Trust’s finances and also our performance against the national four-hour wait target. We will be working in partnership with Monitor and will be fully co-operating with its investigation.
“The trust would like to reassure patients that services are in no way affected by its financial position and patient care continues as normal.”