A mysterious cloud-like object that was spotted hovering over the Philadelphia sky has sparked UFO sighting rumours.

Hector Garcia, a homeowner in North Philadelphia, went outside for a smoke during the July 4th weekend and noticed a strange shaped blob-like object flying over his neighbourhood, the 7th and Tioga street.

In the video footage, Garcia can be heard saying "This cloud has got sparkly lights in it. I have never seen s*** like that in my life."

At first, the object appeared like a normal cloud formation, but to Garcia's amusement, the object started flying across the sky. He claims that the object was transparent and had a twinkling-lights effect.

"As soon as I started recording, it starts to move, it comes down. So I zoomed in on it, and as I zoomed in on it, it starts to swerve. And starts to go to the side. And I'm still looking at it and I don't know what it is. I was shocked," he told FOX 29.

Contrary to Gracia's claim that the mysterious cloud is a UFO spaceship, many YouTube users believe that it could have been a soap bubble blowing in the direction of the wind.

"That's a massive cloud of soap bubbles. The flashing lights are actually sunlight refracted by the thousands of tiny spheres inside the cloud formation," one user wrote in the comments section of the video.

"It looks like a large mass of soap suds to me and not a cloud. Not sure how this would've become air born. Perhaps it blew off of some industrial site?" wrote another.

So far the YouTube video has garnered more than 900,000 views.