Two strikes are to take place next week
The head of the postal workers' union has said he believes a leaked document showing Royal Mail's hard-line stance over strike action is genuine.
The document outlines plans to fight strikes and achieve reform "with or without union engagement".
Communication Workers' Union general secretary Billy Hayes said staff sought to reach an agreement on modernisation.
Royal Mail said the document did not reflect its "policy, strategy or position" in relation to the dispute.
The union has announced two nationwide strikes next week due to an escalating row over pay, working conditions and reform.
The 24-hour strikes will begin on 22 October. On the first day, mail centre staff and drivers will strike. The next day it will be delivery and collection staff.
The document, which was leaked to BBC's Newsnight programme, appears to show Royal Mail digging in for a bitter battle against the union.
Dated 24 September 2009 and marked "In strictest confidence", the document has several chapter headings including Our Objectives, Timeline, Non Agreement and Tactics.
Under the Objectives section the document says that "through the dispute" the Royal Mail will "deliver the necessary 2009 changes with or without union engagement".
And under a section called Tactics, the author of the document says: "Through a mix of pressures bring union to the point where doing a deal on our terms is preferable to the alternative.
EXPECTED STRIKE DISRUPTION
22 October: Limited processing, movement and collection of mail
23 October: Limited delivery and collection of mail
Some managerial staff and contract drivers will be brought in to move mail but services will be "very limited"
Special Delivery and Royal Mail Tracked items will still be delivered on strike days
Post Office branches will be open as usual although collections will be affected
Parcelforce will operate as normal as it has its own collection, distribution and delivery network
Customers should check the Royal Mail website or call 08457 740 740 for the latest service information
Source: Royal Mail
"But if they refuse, we have positioned things in such a way as there is shareholder, customer and internal support for implementation of change without agreement."
Mr Hayes told BBC Radio 4's Today programme: "I'm convinced this is a genuine document and it doesn't seem like management that's prepared to negotiate.
"What's more worrying is that [Business Secretary] Peter Mandelson seemed to know the document quite well. It does seem like an organised attempt to sideline the union.
"What we need is an agreement to modernise the company with the consent of the workforce.
"We want an agreement and we want to negotiate with good faith."
Mr Hayes added: "I hope [Business Secretary] Peter Mandelson is not sitting there, thinking this is my revenge because I could not persuade my parliamentary colleagues to part-privatise the Royal Mail."
But asked about the document by Newsnight, Mr Mandelson said: "Nobody has discussed or raised any such proposition with the government, it is completely new to me."
In the Timeline section, the author of the document talks about the possibility of failure to agree a deal saying: "If un-agreed, consider programme of reducing relationship with union."
Postal workers' representatives are interpreting it as a plan to severely limit union activity, especially because the document also speaks about reducing trade union facilities - which means limiting the arrangement where union staff are permitted to carry out union business while on the payroll.
Royal Mail said it '"did not recognise" the document and responded to a request for a statement on its veracity with the following statement:
"The contents of the e-mail sent to us by Newsnight do not reflect Royal Mail's policy, strategy or position in relation to the current dispute with the CWU.
"No member of the board or the senior management team at Royal Mail has seen, or is aware of any such presentation.
"For the avoidance of any doubt Royal Mail has never had any strategy to derecognise the CWU and nor would we seek to do so."
Meanwhile, a Labour MP has called for the government to mediate between the two sides in the dispute.
Geraldine Smith, who represents the Lancashire seat of Morecambe and Lunesdale, said Lord Mandelson needed to "do more".
She said: "You do need independent arbitration and the government should be leading the call for that really.
"The last thing we need is a national postal strike. That would bring misery to large numbers of business customers. It would have a huge cost to the economy."