The claim is made by lobby group The Disclosure Activists, a new international consortium trying to force the alleged truth about aliens out into the open.

Conspiracy theorists have claimed for years aliens have been visiting Earth and world leaders are aware, but it has been kept from the public under an alleged "truth embargo" amid fears of the impact it would have on religion and the rule of law.

But now The Disclosure Activists claim and number of recent UFO file declassifications, means the lid is about to come off once and for all.

In a statement, the organisation said "the historical stance of widespread denial and misinformation has shifted".

Group, co-founder Russell Calka: "Recently there is a systematic effort from within the US and other world governments to release this information to the public."

Victor Viggiani, the senior strategic adviser to organisation, added: "All of the evidence that has been accumulated by researchers, military witness testimony, and acquired from declassified government documents over the last 70 years points to three very basic conclusions — the planet Earth has been and is being engaged by off-world civilisations.