UP to 100,000 nursing staff will take part in their biggest ever strike next month in a long-running dispute over pay, it has been announced.

Members of the Royal College of Nursing (RCN) in England, Wales and Northern Ireland will take industrial action on December 15 and 20 after voting in favour in a ballot.

Nurses and other nursing staff will take action at half of the locations in England where the legal mandate was reached for strikes, every NHS employer except one in Wales and throughout Northern Ireland.

A separate pay offer has been made in Scotland.

In Wales, union members at six of the nation's seven health boards voted in favour of strikes, but in the Aneurin Bevan University Health Board area the number of votes cast fell short of the 50 per cent threshold, meaning there will be no nursing strikes in Gwent.

The number of NHS employers affected by action will increase in January unless negotiations are held, said the RCN.

The union has repeated calls on the UK government to accept its request for negotiations to resolve the dispute over pay and patient safety.

RCN general secretary Pat Cullen said: “Ministers have declined my offer of formal pay negotiations and instead chosen strike action.

“It has left us with no choice but to announce where our members will be going on strike in December.

“Nursing is standing up for the profession and their patients. We’ve had enough of being taken for granted and being unable to provide the care patients deserve.

“Ministers still have the power and the means to stop this by opening negotiations that address our dispute.”

The RCN said that despite this year’s pay award of £1,400, experienced nurses are worse off by 20 per cent in real terms due to successive below-inflation awards since 2010.

The RCN is calling for a pay rise of five per cent above RPI inflation, saying the economic argument for paying nursing staff fairly is clear when billions of pounds is being spent on agency staff to plug workforce gaps.

The RCN pointed out that in the last year, 25,000 nursing staff around the UK left the Nursing and Midwifery Council register, which explains why there are 47,000 unfilled registered nurse posts in the NHS in England.

Other unions representing health workers including ambulance crews, midwives and hospital cleaners, are also balloting their members on strikes.