Labour MP Tom Watson has published an extract of a letter which suggests Findus knew their product was mis-labelled as early as last Saturday.
He says the letter was passed to him by a retailer which withdrew the affected lasagnes after receiving the correspondence from Findus on Monday.
It suggests that suppliers informed Findus about the "non-conform" on Saturday and that the incorrect labelling could date back to 1st August 2012.
– Extract from letter from Findus to retailers
Investigations have led one of our suppliers based in France to inform us in writing on 2nd February 2013 that the raw materials delivered since 1st August 2012 are likely to be non-conform and consequently the labelling on finished products is incorrect.
The supplier has asked us to withdraw the raw material batches.
Findus said the affected lasagnes were withdrawn from shops on Monday before DNA test results came back on Wednesday.