This is the bizarre moment a young, semi-naked couple were caught on camera having sex on a moving motorcycle.

Police have launched an investigation after the footage, filmed in the city of Encarnacion in south-eastern Paraguay, went viral online.

It was shot by another motorist with a smartphone who could not believe his eyes when he saw the semi-naked couple.

The woman was lying back on the petrol tank with her short skirt hitched up and her legs wrapped around the shirtless male rider.

Many users pointed out that in addition to their incredibly dangerous sexual antics, neither of the young couple were wearing helmets.

Police are believed to be investigating the incident which happened in the Santa Maria neighbourhood of Encarnacion.

Officers are said to be scrutinising the video in an attempt to identify the randy pair.

A police spokesman said that they would face a fine of around three million Paraguayan Guarani (£430) if they were tracked down and convicted.

However, if there was evidence that the biker had been drinking – as seemed likely from the video – he would face a hefty fine and possibly even prison.

Encarnacion is the capital of the department of Itapua and the third-largest city in Paraguay.

In recent years, it has also become the tourism capital of the country, with its wide beaches and newly completed waterfront boardwalk.