Two retailers have been found to be selling contaminated meat products.
Samples of processed beef taken from a county supermarket and takeaway were tested and found to contain traces of pork.
Trading standards officers at Leicestershire County Council have not released any more details about where the outlets are located. They said the items were still on sale.
The two samples are now being subjected to further testing to establish the level of contamination.
A council spokeswoman said criminal proceedings could follow if levels are high.
It comes as horse meat was found in a number of processed ready meals in other parts of the country.
Following the discovery, the Food Standards Agency asked 28 local authorities, including Leicestershire County Council, to test products in their areas.
Leicestershire trading standards officers have tested eight outlets in total. Another five samples are expected to be taken by the end of the week.
So far, no evidence of any horse meat has been found.
David Bull, head of the county council's trading standards service, said: "It's reassuring the samples we have tested so far have proved negative for the presence of horse meat.
"However, two samples did indicate the presence of pork, which was not listed in the label or product description.
"Further testing will now be carried out to ascertain the level of pork present."
Horse meat contamination was first revealed on January 16, after analysis was undertaken by Irish food officials.
The scandal has since spread across Europe. Leicester Mercury Patients' Panel chairman Ballu Patel said: "It's a worry that it's taken this amount of time to uncover, when other local authorities have been much quicker off the mark.
"While the presence of pork may not seem significant it still shows that food is being contaminated and it takes something like the horse meat scandal to bring it out.
"If the horse meat had not been uncovered in the first place then something like this would not have come to light."
Further tests on two beef products served at county schools are also expected back by the end of the week.
The county council has withdrawn beef grill steaks and minced beef from school menus over fears they could contain horse meat.
