National blood centres in 14 locations across England could be affected by a strike involving hundreds of staff over Christmas, a union has warned.
Strike action could affect blood centres during Christmas
The Amicus union is set to ballot its members for strike action in protest over plans to reorganise the service.
The move comes after 81% of Amicus members supported the action in an initial ballot.
A spokeswoman for the NHS Blood and Transplant Authority said the changes were needed to improve efficiency.
The authority runs blood centres in Leeds, Newcastle, Sheffield, Manchester, Liverpool, Birmingham, Bristol, Plymouth, Southampton, Tooting, Colindale in north London, Brentwood, Oxford and Cambridge.
It has announced plans to consolidate some work from the 14 centres into three centres over the next few years but said it had no plans to close the current units.
It has yet to announce detailed proposals.
But Amicus claims the plans would mean the closure of 11 of the centres across England.
Following the initial ballot result Amicus regional officer Owen Granfield said: "This is a wake-up call to senior management who need to sit down with Amicus and talk about the future of the blood service.
"Hundreds of technical and scientific jobs are being put at risk and these are highly-skilled posts which cannot just be relocated to different parts of the country.
"This mirrors exactly what is wrong with the NHS reform agenda because modernisation is being rushed through without consultation with staff or local communities."
More on frontline care
A spokeswoman from the NHS Blood and Transplant Authority said: "We will be investing heavily in modernising how we process and test blood, and we plan to consolidate these functions into three centres over the next few years.
"All services that need to remain close to patients will do so, and it is irresponsible to suggest otherwise.
"Hospitals are now paying £70m a year more for blood than they were a few years ago. We need to become more efficient to allow this money to be spent on frontline care.
"We meet with the unions regularly and are doing so again on Tuesday."