FSA director of policy Steve Wearne said: "It's important that people realise that burgers are not like steak. Harmful bacteria can be carried on the surface of cuts of meat.
"When a rare steak is seared these bacteria are killed, but burger meat is minced so bacteria from the surface of the raw meat gets mixed all the way through the burger.
"These bacteria can remain alive on the inside, unless the burger is fully cooked through, no matter how good quality and expensive the meat."
