A Number 10 source told the corporation: "It isn't acceptable for retailers to remain silent while customers have been misled about the content of the food they have been buying".
Retailers said they would comment on the crisis once the test results on horsemeat in processed meals were available.
The first results will be made public today.
Wholesaler Castell Howell have contacted customers after a 'possible contamination' of cottage pies.
The Food Standards Agency (FSA) has just announced it will extend its UK-wide survey of burgers and similar beef products.
The horsemeat scandal continues to diminish public confidence in the food industry, an ITV News Index poll finds.