Passersby were left shocked after they saw a couple engaging in oral sex on the Algarve strip.

Twitter user, George Fuller, was walking down the Av. Sá Carneiro in Albufeira, Portugal, when he saw a man on his knees, with his head up a woman's skirt.

He, immediately, began recording the man performing an oral sex act on the woman who had her legs over his shoulders as he moved his head up and down.

It appeared that the woman was sitting on a ledge in front of a mobile phone repair shop as the man knelt down on the pavement below her.

Even as Fuller and his friends approached, the couple didn't appear to be bothered as they carried on in full view of passersby.

Fuller shared the video on Twitter and it has now gone viral.

Watch the 18+ video below...