An audacious escape bid has been thwarted after authorities discovered a 20-metre-long escape tunnel beneath an immigration detention centre outside Perth.

Border Force officials have confirmed the escape plan but say none of the detainees got away from the Yongah Hill facility.

Activists from the Refugee Action Coalition (RAC) broke the news on Tuesday, saying the escape bid mirrored one 20 years ago, when 23 asylum seekers dug their way out of Sydney’s Villawood detention centre.

They said the substantial tunnel was discovered on Monday, at a depth of about three metres, and would have taken months to dig.

Escape tunnel to freedom found in Yongah Hill detention centre https://t.co/3gD0Z4nqLC

— RAC Sydney (@rac_sydney) May 10, 2021

It led from under the floor of room 6F, in one of the centre’s accommodation blocks, then ran beneath the inner fences and – almost – to freedom.

A spokesperson from the RAC said the room belongs to a 501 detainee.

That’s a reference to section 501 of the Migration Act, which allows the government to refuse or cancel someone’s visa because they fail the character test, which typically means they have engaged in or been associated with criminal conduct.

In a statement to AAP late on Tuesday, the Australian Border Force said “a suspected attempted escape has been prevented following the identification of a partially dug hole”.

“All detainees have been accounted for and remain in detention. The matter has been referred to the Australian Federal Police …”

-AAP