Cranswick, which also supplies meat for Sainsbury's Taste the Difference range, reduced its price per kg by 2p last Friday, and was followed by Vion shortly after. Woodhead Brothers Morrisons' wholly owned meat processing subsidiary dropped its price by 1p.
The move initially raised serious questions about Oliver's commitment to the British pig industry.
In 2009, the chef fronted a Channel 4 programme that highlighted the importance of supporting struggling British pig producers.
However, following enquiries from The Grocer, Cranswick confirmed the price cut did not apply to those farmers who supplied pork into Oliver's pork range.
Adam Couch, MD of Cranswick's fresh pork operations, said the price cut was "a seasonal adjustment more than anything else" and Cranswick was still paying a competitive price relative to its competitors.
But he admitted the price cut had come at an "inopportune time" for farmers as they battled "extremely high input costs".
The National Pig Association said Cranswick's move nevertheless sent out a worrying signal to British farmers, who had already lost £27m in the run-up to Christmas.
Input costs to pig producers have soared over past months as a result of price spikes on the world grain market.
"Pig producers are already subsidising processors and retailers and their balance sheets cannot stand it not even for weeks, never mind months," the NPA said. "Cranswick's action sends the wrong signals."
Meanwhile, Asda has announced an 8p per kg feed supplement for three months for its Pork Link farmers to help them cope with higher feed costs.