Lord Mandelson today denied union claims that he was orchestrating the postal strike.
The Business Secretary described CWU's accusations as "complete stuff and nonsense from beginning to end".
Lord Mandelson spoke out as he toured the new headquarters of eaga, in Gosforth, Newcastle.
He was officially opening their HQ, called Partnership House, which used to be known as the Northern Rock Tower.
Refuting the union claims he said: "The CWU know that is complete stuff and nonsense from beginning to end.
"What is at the heart of this dispute is the nature and speed of change at the Royal Mail and the modernisation that is necessary to secure its future.
"Of course Government support that, and indeed we have put £1.2 billion on the table to help bring it about, but there is no substitute for the management and workforce agreeing on the detail of how change is going to be implemented.
"That relationship, certainly between the management and parts of the CWU has broken down, and they have got to put it back together again and they have got to do so by talking, by negotiation rather than strike action.
"I hope we will see very intensive discussions between the two sides to avert further strike action next week."
Earlier this week, CWU general secretary Billy Hayes accused Lord Mandelson of being "extremely unhelpful" by "repeating the management mantra that is blatantly untrue".
He added: "While the CWU and management are working hard to reach an agreement, Lord Mandelson is misrepresenting the facts to Parliament and undermining any progress being made in the talks."