Claims patients have been transferred between two hospitals in the middle of the night to prevent bed blocking are being investigated.
The chief of Mid Yorkshire Hospitals NHS Trust said it was unjustifiable for people to be moved from Pinderfields Hospital in Wakefield to its sister site in Dewsbury, in the early hours of the morning.
It followed testimony from Wakefield councillor, Betty Rhodes, that the practice was taking place.
Coun Rhodes, who is chair of the local health scrutiny committee, told a meeting on Friday that she was concerned about the welfare of patients, one of whom she said had been moved at 12.45am.
Others, she said, were being discharged from hospital too early, and without measures being put in place to help them at home.
Under pressure NHS organisations have identified bed-blocking, where patients stay in hospital longer than necessary, as one of the biggest issues facing its day-to-day service as it tries to keep up with demand.
But speaking about late-night transfers and discharges, Coun Rhodes said: "It’s not acceptable and it’s happening.
“It’s not just a case of getting people out of hospital.
"It’s making sure that they’re ready to be discharged and that they’ve got facilities at home to cope and making sure that they don’t have to be readmitted again."
The trust's chief executive, Martin Barkley, said that some patients may go from Dewsbury to Pinderfields in the early hours if they urgently need more specialist care.
But he added that people should not be making the reverse journey in the small hours.
He told the committee: "It is completely unacceptable to be transferring patients at 1.30am.
"I have asked Yorkshire Ambulance Service for details of how many transfers there have been from Pinderfields to Dewsbury in the early hours of the morning.
"I can’t envisage any circumstances where it’s justified to transfer someone from Pinderfields to Dewsbury at that time.
"I can justify it the other way round, because if someone’s condition deteriorates and they need specialist care, going to Pinderfields might be the best option for them.
"I am investigating that."
Local Democracy Reporting Service