The US has been urged to reveal evidence of UFOs after claims made by a whistleblower.

The former intelligence officer said the US government has possession of “intact and partially intact” alien vehicles.

David Grusch claims information on vehicles of non-human origin is being withheld from Congress.

In an interview with the Debrief, Grusch said fragments of non-human craft, and in some cases entire craft, had been recovered over decades.

He said: “We are not talking about prosaic origins or identities. The material includes intact and partially intact vehicles.”

On Tuesday, White House press secretary Karine Jean-Pierre dodged a reporter’s question concerning extraterrestrial life, referring the query to the Pentagon during a White House press briefing.

The claims follow Nasa’s first public meeting on UFOs, held last Wednesday.

The space agency televised the hours-long hearing featuring an independent panel of experts.

The team includes 16 scientists and other experts selected by Nasa including retired astronaut Scott Kelly, the first American to spend nearly a year in space.

Several committee members have been subjected to “online abuse” for serving on the team, which detracts from the scientific process, said Nasa’s Dan Evans, adding that Nasa security is dealing with it.

“It’s precisely this rigorous, evidence-based approach that allows one to separate the fact from fiction,” Mr Evans said.

“I want to emphasise this loud and proud: There is absolutely no convincing evidence for extraterrestrial life associated with unidentified objects,” he said after the meeting.

The study is a first step in trying to explain mysterious sightings in the sky that Nasa calls UAPs, or unidentified aerial phenomena.

The group is looking at what unclassified information is available on the subject and how much more is needed to understand what is going on in the sky, according to astrophysicist David Spergel, the committee’s chair who runs the Simons Foundation.

No secret military data are included, such as anything surrounding the suspected spy balloons from China spotted flying over the US earlier this year.

The meeting was held at at Nasa headquarters in Washington with the public taking part remotely.

A final report is expected by the end of July.