Archaeologists in Peru working on a site in the outskirts of the capital Lima have unearthed a mummy believed to be between 800 and 1,200 years old - and, surprisingly, bound with rope.

The remains are thought to be of a man aged 18-22 at the time of his death, with his hands covering his face.

The mummy was found in a burial chamber that is about three meters long and at a depth of about 1.4 meters at the dig site in Cajamarquilla, about 24 kilometres east of Lima.

Archaeologist Pieter Van Dalen, who oversees the Cajamarquilla project, called the find "peculiar and unique".

"The mummy would have been buried sometime between 800 and 1200 AD," he said - meaning it would be at least 800 years old.

On one side of the mummy, experts found the skeleton of an Andean guinea pig and what appears to be a dog, according to the researchers at the University of San Marcos.

Traces of corn and other vegetables were found in the burial chamber.

Cajamarquilla was an urban centre that could have been home to 10,000-20,000 people, Mr Van Dalen explained.

The city was built in around 200 BC and was occupied until about 1500.