To: Mr Supermarket Buyer Re: Aren't you just a bully?

Supermarket buyers are "too well briefed, too disciplined and too cute" to leave electronic audit trails exposing their bullying tactics to investigators at the Competition Commission, manufacturers have claimed.

The Commission has served legal notices called Section 109s, on Tesco and Asda requiring them to hand over emails exchanged with suppliers as part of its investigation into the groceries market. But it was "highly unlikely to find anything wildly incriminating", predicted the commercial director at one chilled goods firm. "Regulators have been breathing down the necks of the big four [supermarkets] for longer than I can remember," he said. "I would be incredibly surprised if buyers at Tesco or Asda have slipped up in this way. They are too well briefed, too disciplined and too cute for that."

Anything unpleasant that a buyer wished to communicate was typically done face-to-face or on the phone, which left no audit trail, added the md of one confectioner. "These conversations will then be followed by an anodyne email along the lines of, 'Just writing to confirm what we discussed yesterday ...', " he said. "I assume the commission is basing this line of inquiry on specific information from suppliers; if not, I wish it luck. Conversations of the type it is looking for take place behind closed doors by consenting adults."

He added: "If you want to communicate anything contentious, the company email account is not the place to do it."

The commission confirmed that it was acting on specific information from suppliers as part of its continuing inquiry. "We are not planning to trawl through millions of emails at random in a bid to find something incriminating."

Tesco and Asda both agreed to co-operate. Tesco said: "Relationships with our suppliers are professional and act to the ultimate benefit of the customer."

Asda chief executive Andy Bond dismissed the allegation that his buyers were demanding discounts in a "threatening and aggressive manner" as "nonsense" and "hearsay". However, manufacturers claimed that Asda was "one of the worst" supermarkets for extracting money from its supplier base.

One said: "Fines are used as a pure money-making exercise - they find something wrong so they can make some cash. That's then deducted from you, so if you query it, you're always on the back foot, trying to claw your own money back. It's beyond outrageous."

In a recent online poll conducted by Food Manufacture, 68% of food and drink manufacturers claimed to have been subjected to supermarket bullying.