Members of the US Congress held a joint hearing by subcommittees of the House Oversight Committee on Wednesday to discuss the existence of Unidentified Anomalous Phenomena (UAP), also known as UFOs.

During the hearing, Congressman Tim Burchett from Tennessee entered into the Congressional Record a document about an alleged secret UAP program named "Immaculate Constellation."

"The first section talks about the unacknowledged special access program called Immaculate Constellation and the second section about USG imagery intelligence," said Congresswoman Nancy Mace of South Carolina, who chaired the hearing along with fellow Republican Glenn Grothman of Wisconsin.

Ex-intel officer says US hiding info on alien craft

Asked during his testimony if there had ever been any communication with a non-human lifeform, former US Army Counterintelligence employee Luis Elizondo said there had been 'nonverbal' communication.

"I would say definitively yes, but from a non-verbal meaning. When a Russian reconnaissance aircraft comes into US airspace, we scramble to F-22s. And we are certainly communicating intent and capability. I think the same goes with this. We have these things that are being observed over controlled US airspace, and they're not really doing a good job hiding themselves. They're making it pretty obvious they have the ability to even interfere with our nuclear equities," he said. 

US gov't examining over 500 'UFO' reports

According to a press release, the hearing was intended to "pull back the curtain on secret UAP research programs conducted by the US government, and undisclosed findings they have yielded."

In March, a Pentagon report said US government investigations since the end of World War Two have found no evidence of extraterrestrial technology and had concluded that most sightings were misidentified ordinary objects and phenomena.

NASA joins the still controversial search for UFOs

(Production: Jane Ross)