Speculation was mounting today that Royal Mail is to make a statement on its finances which could lead to thousands of postal workers not receiving a bonus they were expecting.
The move could come as early as tomorrow, alongside a warning that Royal Mail's share of the postal market was falling.
It would be the first major announcement by Moya Greene since she took over from Adam Crozier as chief executive last year, with the business facing increased competition.
Royal Mail has been pressing ahead with modernisation plans since a bitter strike involving members of the Communication Workers Union was resolved in 2009.
Former chairman Allan Leighton launched a so-called colleagueshare scheme in 2007, with workers being told they could receive up to £5,300 over the five-year plan, combined with other dividends.
Rumours started last week in several areas of the country that the money will not be paid out this year because of the state of Royal Mail's finances.
Postal workers have been waiting for news about the expected payout, with some saying it was worth several hundred pounds.
The Government has launched controversial plans to privatise Royal Mail, with legislation being considered by the House of Lords.
Neither Royal Mail nor the CWU would make any comment today.
Unite said staff had been told that the performance of the company was such that the colleagueshares were worth nothing.
The union also claimed that Royal Mail was planning to close south and east London mail centres, with a future focus for central London being in Mount Pleasant.
In a letter to the company, national officer Brian Scott said: "I am bitterly disappointed that, despite your previous commitment, Unite has learned today that Royal Mail is communicating directly with employees in the issue of potential job losses before it has started consultation with the union.
"I really must impress upon you that if this is the future style of industrial relations and engagement between Royal Mail and Unite then this will only make life difficult for everybody.
"You will gather from the above comments that the situation is unacceptable to us and demand that we meet with you as a matter of extreme urgency to discuss the way forward."
Mr Scott said: "Royal Mail has failed in every way to achieve its objectives of rewarding individuals in the longer term for the valuable contribution they have made to the improvements and success of the business.
"This situation has been handled very badly by the company and Unite is demanding an urgent meeting."