LONDON - ARCHAEOLOGISTS have unearthed a human brain in northern England that dates back to the Iron Age, York University officials said on Friday.

The brain, which is at least 2,000 years old, is the oldest ever discovered in Britain, and thought to be one of the oldest found anywhere in the world.

It was chanced upon when the York Archaeological Trust began exploratory digging as part of a planned expansion of the university campus, with a trust officer noticing a skull in a muddy pit, leading officials to believe it was used as a ritual sacrifice.

While expert Rachel Cubitt was cleaning the skull she found a yellow substance inside. 'It jogged my memory of a university lecture on the rare survival of ancient brain tissue,' Cubitt said.

'We gave the skull special conservation treatment as a result, and sought expert medical opinion.'

The skull was found in the Heslington district on the outskirts of York, in an area of prehistoric farm land dating back to at least 300 BC.

University officials used a computed tomography scanner to produce images of the skull's contents. -- AFP