Leicestershire Police said three incidents were reported, with the drone activity understood to be related to the Download Festival at nearby Donington Park.
The first incident was reported at around 9.30am on Saturday, followed by another at midnight and third at around 1.30pm on Sunday.
Officers interviewed the operator of the drone sighted on Saturday morning, but those operating the other two are yet to be identified.
The CAA and East Midlands airport are assisting police enquiries.
A Leicestershire Police spokesperson said: “We are aware of three incidents where an unmanned aerial vehicle has been flown in restricted airspace near to the Download Festival at Donington Park.
“Due to the incidents taking place in close proximity to East Midlands airport, a number of flights were temporarily delayed as a result of each report.”
A East Midlands airport spokesperson added: “A Tui flight bound for Larnaca and a Ryanair flight to Pisa experienced minor delays departing East Midlands airport on Sunday due to the sighting of an unmanned aerial vehicle over the Download Festival site.”
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