The US Air Force KC-135 aircraft took off from Amiens in northern France shortly after midnight local time – but vanished from tracking websites 15 minutes later.
The Boeing plane is used to refuel jets mid-flight and can carry up to 31,000 gallons of fuel.
It is not known why the plane, which uses the callsign QID72, declared an emergency.
A US Air Force spokesman declined to comment when contacted by Express.co.uk.
The Ministry of Defence said it did not have any information on the apparent vanishing of the jet.
Around 36 of the aircraft have been involved in crashes in the past.
In March 1985 one of the planes caught fire at Cairo International Airport in Egypt, completely writing off the jet after its interior was burned out.
And in 1972 a French Air Force C-135 lost power on one engine and crashed into the sea killing all six crew members on board.