The phlebotomists are paid £12.08 an hour on Band 2 of the NHS Agenda for Change pay scale, but Unison says their skills and responsibilities mean they should be paid at the higher Band 3.

The union says the workers also deserve back pay to compensate them for being incorrectly banded since 2018.

Unison South West regional organiser Chris Roche said: ‘These dedicated staff play a vital role in the health service. They should be focused on patients, rather than worrying about whether they can pay their bills.

‘Phlebotomists couldn't be blamed for leaving for better paid work elsewhere, worsening the NHS staffing crisis. But instead they've chosen to stay for their patients, and campaign for fair pay. The trust must do the right thing now to avoid industrial action.'

The phlebotomists, who asked Gloucestershire Hospitals NHS Foundation Trust to put their pay right over a year ago, voted unanimously in favour of a strike ballot during a recent consultation. They will be balloted until Tuesday 18 February.

In response, a trust spokesperson, said: ‘We recognise and appreciate the valuable contribution that our phlebotomists make to the care of our patients.

‘We will continue to work closely in partnership with our local union representatives and phlebotomists to explore an amicable resolution.'