Thousands of nurses have marched through central Melbourne, as Victorian public hospitals crank up their case before the industrial umpire in a bitter pay and conditions dispute.

Nurses, who say they won't budge on the preservation of nurse-to-patient ratios, gathered in Bourke Street Mall on Thursday and made their way to Parliament House.

They are continuing to close beds and cancel elective surgery, despite being ordered to stop industrial action by Fair Work Australia.

Some 273 beds remained closed and 108 operations were cancelled on Thursday.

Hilenia Zaami, who has been a nurse for 20 years, said nurses were disgusted by the government's lack of respect for their work.