Archaeologists hoping to uncover remains of 'Port Jorvik'

They would mean digging down to a depth of up to 30 feet looking for evidence of Viking, Anglo-Saxon and Roman riverfront activity - while the Coppergate Riverside development continued overhead.

If exciting remains - say of a Viking or Roman waterfront or port - were found, the excavation could be turned into a Time Team-style open dig with members of the public being invited to watch archaeologists at work, says the York Archaeological Forum, which is behind the proposals.

City archaeologist John Oxley will tomorrow be meeting environmental engineers employed by Land Securities to discuss the proposals.

Nobody knows for sure what lies beneath the Piccadilly side of the Foss, though initial exploratory trenches dug during the 1990s revealed the possibility of medieval, Viking and Roman remains. The chairman of the York Archaeological Forum, John Hampshire, said the site was particularly exciting because any archaeology there would have been protected by being waterlogged. Such a dig may unearth waterfront remains as exciting as anything found in the Jorvik dig - or it may reveal little other than a few artefacts, Mr Hampshire admitted.

"There could be some wharfage down there: there could be a Roman boat that sank there with amphorae full of wine, or that was being loaded with materials produced locally. That would tell us an awful lot about life and conditions in York," he said.

The idea would be to carry out the dig beneath a specially-constructed floor while development went on overhead, a method that has been used successfully in Cologne.

The Forum, which advises the city council on archaeological issues, is worried that if the archaeology of the site is not explored now - the city council's usual policy is to 'preserve it for future generations' - it could be damaged. There are some fears that development may cause the site to dry out and damage conditions that had preserved remains. But Mr Oxley said this was unlikely.