The appeal for as many independents to take out membership comes as ACS has again urged the government to introduce safeguards for the whole grocery sector.
Chief Executive David Rae said: “The implications of this latest acquisition by a multiple retailer will be felt widely and acutely in our sector. We must fight for fairness in our industry, and I urge all independents to join us now to help our campaign for balance and true competition in the sector.
The UK’s third largest grocer doubled the size of its convenience store operation with the deal, which cost more than £100m.
Sales at Jackson’s Stores reached £143m for the financial year ending April 24, and it had net assets of £25.5m.
The stores will gradually be rebranded as “Sainsbury’s at Jacksons”, which follows the success of the “Sainsbury’s at Bells” convenience stores.
Elsewhere, Sainsbury has delayed its plans for a new distribution depot in Berkshire due to planning restrictions.
The Times reports that the ACS is seeking a meeting with the Office of Fair Trading to ask it to refer the Sainsbury’s deal to the Competition Commission.