A source at Abbey said: "If they [N&P] are trying to get away with just offering their members tea and cakes at today's annual meeting, it won't work."
The bank, which converted from being a building society in 1989, hopes enough N&P members will be tempted by the prospect of up to £750 worth of shares each, assuming the society is valued at around £1.4bn.
Abbey's tactics were yesterday rebuffed by the N&P board, which said it would not be "bounced" into any such course of action. N&P members willhave the chance to voice their opinions at the society's annual meeting - but it is unlikely that they will get further information on Abbey's proposal.
The board said: "N&P has been examining its future strategy in some depth over the last few months. As part of this process, N&P has been receptive to the thinking of relevant third parties and is continuing to have discussions with a number of them."
Abbey National had asked for a meeting and it had been agreed that its chief executive Peter Birch would meet with N&P's counterpart Alastair Lyons. It therefore "came as a surprise that Abbey National issued a unilateral press statement yesterday," N&P said.
Meanwhile, Bradford & Bingley denied that its attack on Abbey National on Monday signalled a merger with N&P, saying its concern had been "to defend mutuality in the interests of building society members."