Italy's La Gazzetta dello Sport reported that a couple of handsful of engineers from rival teams have started work at Maranello, including a trio who previously worked on Mercedes' currently-dominant turbo V6 power unit.
But Mercedes team chairman Lauda insisted at Silverstone: "We have all the important engineers firmly under contract.
"They are staying," the great Austrian reiterated. "We have long term contracts with our major engineers."
Germany's Auto Motor und Sport said one of them is Mercedes' most important engine man, Andy Cowell, who is under contract for the next five years at least.