Motorist Gary McDermott says he photographed the shimmering red craft, complete with flashing lights, after stopping to snap a low-flying helicopter in Plymouth.
The object, which McDermott claims was disc-shaped, flashed across the sky at 9pm on Sunday – just as he was taking the picture – before it vanished.
“I just couldn’t believe what I had just seen,” McDermott told the Telegraph.
“It must have been a UFO – and I cannot believe I am saying that because I don’t believe in them usually. I am always sceptical.
He said it was “definitely not” a normal aircraft.
“It was red, the shape they say UFO aircraft is, and had two bright lights coming out of it.
“Apparently there have been a few other similar sightings across Britain in recent weeks.”
On January 6, there were anecdotal reports of two bright lights floating over Kent. Days later, four similar lights were seen over Essex.
Devon and Cornwall Police said they had received no reports of any UFO sightings.