The manhunt for an Australian tourist accused of an outdoor sex act in Bali has ended in an airport arrest.

CCTV footage from a North Kuta villa captured a man and woman walking down a driveway, before the appear to double back and begin having sex against a partially closed fence on Saturday, police allege.

They were laying on the floor when footage shows a local woman round the corner and catch them in the allegedly illegal act.

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Public acts of indecency and sex outside marriage are both illegal in Indonesia, and foreigners caught fornicating can face jail time.

The witness to the alleged sex act on Saturday could be seen stopping in her tracks in CCTV footage of the moment, and calling out to the unmoving couple before fleeing in the direction she came from.

Police used the footage to identify one of the suspects, a 27-year-old Australian man.

He was about to catch a flight to Brisbane when was stopped by inspection officers at Gusti Ngurah Rai Airport on Tuesday.

Badung Resort Police have now taken over the investigation.

The woman involved in the alleged sex act has not yet been arrested.

Local police continue to search for the female foreigner, and investigate the alleged crime.

CCTV shows a man and woman walk past the outdoor spot, before returning seconds later to allegedly have sex there. Credit: Supplied

A local woman caught the pair in the alleged act. Credit: Supplied

Authorities shared images of the ‘tersangka’, which translates to ‘suspect’, in custody. Credit: Supplied