Patients diverted from Antrim hospital to Coleraine for 8 hours
Concern has been voiced after a plan was put in place for more than eight hours to divert patients away from Antrim Area Hospital.
Instructions were issued for patients to be taken to the Causeway Hospital instead, a 45-minute drive away.
The diversion was initially in place between 10am and 2pm – but was later extended to 6pm.
It is understood that the diversion was put into place because of resource issues, but did not affect the emergency department.
Alliance MLA Stewart Dickson said he was highly concerned about what had happened.
"While I understand that there was only minimal disruption, I am concerned that this is the latest in a series of measures put in place at various hospitals due to resource issues," he said.
"The Health Minister must take urgent action to prevent any such measure being put in place again.
"While there are questions over the Health Minister's performance, I have to pay tribute to the hard working and dedicated staff in our hospitals. They are doing a magnificent job."
A spokeswoman for the Northern Health Trust emphasised that this type of diversion is relatively common within trust areas.
She said that no patients were affected by it.
"It's not unusual and the measure is designed to keep patients flowing through hospitals," she said.
This latest incident comes at a time when pressures facing emergency departments across Northern Ireland have been hitting the headlines.
Last weekend, emergency departments across Northern Ireland struggled to cope.
The Belfast Health Trust triggered "escalation plans" which included additional beds being opened at the Royal Victoria Hospital (RVH).
Health union officials slammed the situation at the RVH last weekend as "mayhem" and claimed that at one point last Sunday night there had been 96 patients on trolleys awaiting admission.
The emergency departments at the Ulster Hospital in Dundonald and Antrim Area Hospital were also very busy.
At the start of January, a major incident was declared at Belfast's RVH due to a large backlog of patients at the emergency department
The Belfast Health Trust admitted that delays in treatment may have been a significant factor in the the deaths of five patients at the RVH in 2013.
The Department of Health is currently conducting a review into the provision of emergency services across Northern Ireland.
In November 2011, Belfast City Hospital's emergency department closed its doors and the RVH became the main hub of emergency care in Belfast.
The pressure on hospitals has rarely been out of the headlines this year. Emergency departments across Northern Ireland were in crisis last weekend with the Belfast Trust triggering 'escalation plans' at the Royal Victoria Hospital.
That came just weeks after a major incident was declared at the same hospital. Emergency Department nurses said last month that they feel "battered and bruised" by the pressures they are regularly working under.