In a letter to trade unions, the company admitted its “very tight financial position” might render it unable to offer any staff a pay rise this year.
In his letter, Royal Mail’s HR director, Jon Millidge, said: “Given the tough economic conditions and with the retail price index currently being negative, you will undoubtedly be aware that many other companies find themselves in a similar position of having difficulty in affording increases in pay.
“We do not envisage being able to increase pay rates for any colleagues (including all directors and managers) across the group.”
Millidge added that previous commitments on pay would still be honoured.
Dave Ward, general secretary of the Communication Workers’ Union, said the decision was “outrageous”.
He said: “Postal workers are first class – they don’t deserve this second-class treatment. Royal Mail posted its best financial results for years in December and outperformed all of its financial targets. Rewarding staff with a pay freeze is appalling. The people who run Royal Mail have again misjudged an important decision.
“For the UK’s highest-paid civil servant to impose a pay freeze on workers who earn less than the UK average wage is outrageous.”
Ward added the decision will make industrial action “inevitable”.