"We are considering a number of options," said NMA committee member Ian Hunt. "You cannot sell the family jewels on the eve of such an important decision."
Hunt, who is managing director of Welsh grocery chain Filco Foods, said that one measure was a campaign to persuade Costcutter retailers to switch to Nisa-Today's independently, thus diminishing Costcutter's customer base and making the prospect of a merger less attractive.
"We have a letter drafted and ready to go out to all Costcutter retailers, telling them that there is nothing legally to stop them ending their contract with Costcutter and moving over to Nisa," he claimed.
Hunt argued that the only thing stopping retailers was a gentleman's agreement between Costcutter and Nisa-Today's not to approach each others' retailers, and cited the example of Hugh Griffiths, a forecourt retailer in Bridgend.
Hugh gave six months' notice to Costcutter before closing both his shops temporarily and subsequently reopening as a Nisa-Today's member.
A spokeswoman for Nisa-Today's refused to comment on the sale of the warehouse. She claimed details of Nisa-Today's board meetings were confidential. She added that although due diligence was mostly complete, certain parts had not been finished and thus the full terms of the merger were still not finalised.