Updated 12.43pm: US police have given the all clear after searching two planes at Atlanta's main airport after authorities received bomb threats on Twitter.

Following the threats yesterday, two F-16 fighter jets were sent to escort a Delta flight and a Southwest flight safely to Hartsfield-Jackson Atlanta International Airport.

Preston Schlachter from the North American Aerospace Defense Command (NORAD) says a Twitter user made threats earlier in the afternoon regarding smuggling bombs aboard the aircraft.

He described the escort as a precautionary measure.