Royal Mail workers have voted overwhelmingly to back further strikes.
Members of the Communication Workers Union (CWU) have voted in a second ballot to enter into a formal dispute with management over pay and conditions.
Members voted by 98.7 per cent on a 72.2 per cent turnout.
An earlier vote in July had seen some 97.6 per cent vote ‘yes’ on a 77 per cent turnout for strike action over pay.
Posties are already planning industrial action on 26 and 31 August and on 8 and 9 September.
CWU general secretary Dave Ward said: “Today’s result is another rejection of those at the top of Royal Mail, who should consider their positions.
“Postal workers in this country are being pushed to the edge, but there can be no doubt that they will fight the planned erosion of their workplace rights with determination.”
The Royal Mail was losing £1m a day and needs to change to “fix the situation and protect jobs,” a spokesperson for the postal service said.
Changes were needed to support a pay offer worth a 5.5 per cent increase, the Royal Mail said.
“This is the biggest increase we have offered for many years and the CWU have rejected it,” they added.
However, union bosses said they would “fight this disgraceful state of affairs every step of the way.”