HIGH-definition video shows a mysterious cube-shaped UFO appearing to hover over a major city.

A commercial jet is seen flying close by the silvery craft, which was reportedly filmed near an airport on Monday.

Lorna Mosquera posted footage on YouTube he said was filmed on 4K mode on his iPhone 13 Pro in Medellin, Colombia.

It shows the view from his apartment balcony, looking over other tower blocks and mountains in the distance.

A dark object can be seen a few thousand feet up, and he zooms in to show a closer view of what appears to be a metallic cube or diamond.

“Guys, what the hell is that?” he is heard asking on the clip.

Lorna, who calls himself a UFO sceptic, wonders aloud in the video if it could be a weather balloon but then rules that out.

He says: “Look at the shape though.

“I swear to God, I have no experience on Photoshop or whatever. You can examine this video how much you want.

“Bro, what the f*** is that?”

A plane then flies into view, not far from the cube.

Lorna pans round to show its landing path to the city’s airport.

He adds: “If that’s a UFO, Medellin is a city full of cell phones. So we’d hear about it.

“This is the first time in my life that such a thing has happened to me, like a UFO sighting whatever.

“I’m a huge sceptic, like huge, but also… what the f*** is that?”

Lorna said he ended the video there so he could Facetime his family and show it to them live.

He said the object was “dead still” for eight minutes, then “started drifting behind the mountains”.

He added: “I have more similar footage (but freaking out haha).”

One viewer replied in the comments: “Bro upload all photo, video whatever you have. This is one of best UFO video I ever seen.”

Another said: “This is crazy good footage.”

String theory

Not everyone was convinced, however.

One said: “That’s a typical tethered hot air balloon. Nothin new, nothin mysterious.”

But Lorna said: “That’s the most improbable explanation.

“Strings so long and strong/modern that they keep an object bigger than an airplane in place, miles above sea level… All of that in a no-fly zone too?

“Those strings would break the airplane flying near that thing lol.”

It is not the first strange sighting over Medellin.

In February 2020, the pilot of an Airbus A320 used his phone to capture a dark cube or “polyhedron” at 30,000ft.

UFO watchers have recorded a number of sightings of cube-shaped objects they believe could be alien craft.

In November, a mysterious spinning cube was filmed over two cities in Ohio and Missouri hours apart.

Weeks earlier, another video claimed to show “dark cube” UFOs near the famous Area 51 facility in Nevada.