Hospital patients and residents of homes for the elderly won't be washed or changed under new union directives, the health commissioner has warned. 

Charles Messina condemned the measures as an "attack on the most vulnerable" and said they "go against the dignity of the human being". 

He did not name which union was involved in issuing directives that also include not helping patients mobilise. 

Patients and residents who are incontinent will be most affected by the measures, he said in a statement on Wednesday. 

Last week Messina said elderly St Vincent de Paul Hospital patients were being left unwashed for days as a result of union directives.

He said patients were being used as "pawns" to pressure the authorities.