Arab Bedouin tribesmen stand at the entrance of a cave complex near Petra, Jordan, where 2,000-year-old Nabataean wall paintings have been restored. (Ali Jarekji/Reuters)

British archeologists have completed conservation of rare wall paintings near the city of Petra, Jordan, that are more than 2,000 years old.

The World Heritage site is known for its city carved out of rose rock, but archeologists say the art is the best indication the city was once covered in paintings.

The paintings, unveiled last week after a three-year restoration, are believed to be the only surviving example of the art left behind by the Nabataeans, who lived in the mountainous region in the 1st to 5th century.

A figure in one of the 1st century paintings reflects the Hellenistic influence in ancient Petra and the bright colours that may have once adorned much of the city. (Ali Jarekji/Reuters)

The Nabataeans were among the most successful merchants of their day and built the spectacular city of Petra as their capital.

Their paintings reflect influences of other cultures where they would have traded, according to experts at London's Courtauld Institute of Art.

"In Petra there is so many influences. There is a Syrian, there's Egyptian, Roman, Hellenistic and there is also indigenous Nabataean architectural forms as well," said conservation expert Lisa Shekede, a member of the team overseeing the restoration.

"In the figure style of the painting and in the naturalism of the representations of the birds and the wines, Hellenistic influence seems to be quite strong."

The paintings portray a wine harvest, with human figures, resembling the god Dionysus, celebrating. There are also birds, including a demoiselle crane and a Palestine sunbird with rich colours.

The Nabataeans used gold to highlight some of the images.

They were found in a cave complex at the canyon of Siq al-Barid in Beidha, known as 'Little Petra," about five kilometres from the main site.

The most outstanding painting covers the vault and the walls of a small recess where it is believed people dined.

The Courtauld restoration team found the paintings in state of severe deterioration, covered with soot from fires from local Bedouins who use the caves for shelter. The paintings had also been damaged by graffiti and attempts to chip them off.

Stephen Rickerby, a British conservation specialist from the Courtauld Institute in London, works on the vaulted ceiling where the ancient paintings were found. (Ali Jarekji/Reuters)

"It has actually been quite nerve-racking," said conservation expert Stephen Rickerby.

Rickerby said the team's priority was to stabilize the paintings, and they initially thought it would be impossible to clean them.

However, the paintings they were able to uncover are "really exceptional and staggeringly beautiful, with an artistic and technical quality that's quite unlike anything else," Rickerby said.

They also reveal much about the rich culture of the Nabataeans, he added.