TEHRAN — Iran has material evidence to prove that it has captured an American unmanned aircraft, a prominent lawmaker in Tehran said Wednesday, rejecting US Navy statements that none of its drones in the region was missing.

On Tuesday, Tehran said it captured a Boeing-designed ScanEagle drone after it entered Iranian airspace over the Persian Gulf and even showed an image of what it said was the aircraft on state TV. The Islamic Republic trumpeted its possession of an allegedly intact US drone as another prize in its growing showdown with Washington over surveillance of Iran’s disputed nuclear program.