Staff at Llandough Hospital in South Wales have passed a unanimous vote of no confidence in its managers after a decision to close two wards.
A mass meeting of Unison and Royal College of Nursing members also accused the trust of undervaluing nursing staff and failing to address problems caused by using agency nurses.
Chief executive Norman Mills said the wards had to close because the trust needed to claw back a 2m overspend over four years.
'We were spending over 1m a year on agency staff to maintain our medical emergency cases,' he said. 'This became financially untenable.'
An RCN spokesperson said nurses employed by the trust often did extra hours through an agency, rather than on the trust's overtime rates, which were much lower. Dr Mills said basic grade nurses were being paid 8 an hour by the trust, but could get three times that with one agency.
The trust will offset some of the impact of the closure by funding 30 community care packages for patients awaiting discharge from hospital. Dr Mills said the arrangement would save the hospital 225,000 a year.
But RCN spokesman David Wallace claimed there had been no consultation about the move.