The White House has said it has no evidence that extraterrestrial creatures exist.

Barack Obama's administration made the declaration on Monday in response to feedback on its website, which allows people to submit petitions to which officials must respond if enough people sign.

In this case, more than 5,000 people signed a petition demanding that the White House disclose the government's knowledge of extraterrestrial beings. More than 12,000 signed another petition seeking formal acknowledgment of an extraterrestrial presence engaging with the human race.

In response, Phil Larson of the White House office of science and technology policy wrote that the US government has no evidence that life exists outside Earth, or that an extraterrestrial presence has contacted any member of the human race.

"In addition, there is no credible information to suggest that any evidence is being hidden from the public's eye," Larson wrote.

However, he did not close the door entirely on a close encounter of an alien kind, noting that many scientists and mathematicians believe the chances are high that there is life somewhere among the "trillions and trillions of stars in the universe" – although the chances that humans might make contact with non-humans are remote.

It is not the first petition to force the White House to engage on a somewhat offbeat topic since the "We the People" web page was inaugurated in September. Various petitions demanding the legalisation of marijuana have gathered more than 100,000 names, to which the White House has responded that marijuana is associated with addiction, respiratory disease and cognitive impairment, and legalising it would not be the answer.

The administration has also addressed topics including gay marriage and student loan debt.