If there are extraterrestrial rewards for perseverance, the organisers of the UFO conspiracy hearings that are under way at the National Press Club in Washington this week deserve a visit from space.

Five former US congressmen and one former senator have been paid $20,000 each to lend credibility to the event, which calls on the government to release supposed secret documents showing alien incursions dating back decades.

Expert witnesses were sworn in under oath to testify before the committee of former politicians. UFO watchers from around the world were patched in via live video link and booths of simultaneous translators provided coverage in Spanish, Arabic, Hindi, Japanese and Mandarin. Even the Nation of Islam leader Louis Farrakhan paid a visit, complete with a dozen security guards.

Not one of those who spoke during an opening session filled with around 100 delegates disputed the premise that extraterrestrial visits were being hidden from the public.

In 2011, the White House responded to a petition on the subject by formally denying any such cover-up. "There is no evidence that any life exists outside our planet, or that an extraterrestrial presence has contacted or engaged any member of the human race," the White House response said. "In addition, there is no credible information to suggest that any evidence is being hidden from the public's eye."

But that official intervention has only served to stoke anger among those who believe in a vast government conspiracy.

More than 10,000 separate UFO sightings are reported each year to two leading conspiracy websites, according to one witness, Richard Dolan, who has written several books on the subject. Linda Moulton Howe, a former documentary filmmaker, said that aliens had been visiting earth "since before the dinosaurs". "We are dealing with technology so advanced that they can bend space and time," she said, to loud applause.

The politicians who made up the committee were given just five minutes each to cross-examine witnesses, but defended their presence and the $20,000 "honorarium".

"I would not have come if I thought it was damaging to my reputation," said California Democrat Lynn Woolsey, who retired from Congress this year after 10 terms in office. "I am here because I believe in transparency."

Roscoe Bartlett, a Tea Party Republican from Maryland who served 10 terms in Congress and chaired a sub-committee of the House armed services committtee, said: "Extraterrestrials are not anti-biblical. Read the book of Job – it's all there."

Senator Mike Gravel, a Democrat who represented Alaska for 22 years, added: "It is the height of human arrogance to think that we are the only sentient humans [sic] in the universe that can think."

Witnesses gave a variety of reasons for the persistence of the cover-up, even after the end of the Cold War. Stanton Friedman, who has two degrees in physics, said: "If there were something announced, say by the pope and the Queen, what would happen? Young people would see themselves as Terrans and would lose their allegiance to nations. No government could allow that."

Only one politician, Carolyn Kilpatrick of Michigan, a Democrat, complained about the process of the "pseudo hearing", asking why the committee had not received written evidence in advance.