Over 8,000 patients nationally were admitted to hospital without a bed in June, according to the Irish Nurses and Midwives Organisation Trolley Watch figures.

Sligo University Hospital had the second worst level of overcrowding nationally for the month, with 822 patients on trolleys waiting for beds.

University Hospital Galway was the fourth worst nationally with 637 patients on trolleys waiting for admission this month.

University Hospital Limerick had the worst level of overcrowding, as 1,689 patients waited on trolleys for admission.

Mayo University Hospital had the highest number of patients in its Emergency Department waiting for a bed this June than it has ever recorded, at 435 .

That figure is up significantly, 25 percent,  on last year when the number was 333.

In 2006,  when Trolley Watch records began the number of patients waiting on trolleys for admission to Mayo University Hospital was 132.

Portiuncula University Hospital had 142 patients on trolleys waiting for beds this month.