Hundreds of staff at the British Medical Association (BMA) are to stage a one-day strike next week, a day before doctors take industrial action in their row with the Government over pensions.
The GMB, which represents around 400 workers at the BMA, said the walkout would be held on June 20 in a dispute over pay.
Doctors will take industrial action on June 21, for the first time in almost 40 years, in protest at the Government's controversial pension reforms.
GMB members backed industrial action by 4-1 in a recent ballot after they rejected a pay offer of 1.5% plus an additional 0.5% for high performers.
The union said that under a grading re-structuring, the offer was only worth 1.2% for most workers.
GMB official Tony Warr said: "The BMA is aware that our door remains open in order to reopen negotiations to achieve a settlement.
"The 24 hour strike action will take place at all BMA locations throughout the UK and the strength of feeling remains overwhelmingly in support of the action which, of course, is the last resort.
"Our members did not want to go down this route but unfortunately management have given us no option whatsoever.
"The BMA Council should practice what it preaches in terms of achieving a negotiated settlement.
"As the BMA prepares for the first industrial action by doctors in 40 years, they should enter into talks to avert industrial action by its own staff.
"The BMA rightly expects the government to negotiate in good faith and they should do the same."
- More about: