The US Department of Defense on Wednesday dismissed a Republican lawmaker's claim that an Iranian "mothership" had been stationed off the US East Coast, launching drones over New Jersey military sites.

"There is not any truth to that. There is no Iranian ship off the coast of the United States and there’s no so-called mothership launching drones towards the United States," Pentagon deputy press secretary Sabrina Singh told reporters on Wednesday.

In an interview with Fox News earlier in the day, New Jersey Congressman Jeff Van Drew cited "very high, qualified, and responsible sources" saying "Iran launched a mothership probably about a month ago that contained these drones."

“These drones should be shot down,” said Van Drew, who sits on the House Transportation and Infrastructure Committee. He was referring to large drones that have been seen gliding through New Jersey's night skies for weeks, puzzling residents with their mysterious flashing light displays.

Singh added there was no evidence that the reported drone flights were "the work of an adversary”.