The Minister for the Environment, Mr Cullen, is set to order a full archaeological excavation of the Viking site at Woodstown in Waterford, even though it will delay the city's bypass by at least a year.
Mr Cullen said the site, which dates from the ninth century, was of "enormous importance internationally" and had already yielded some "quite extraordinary" finds, including lead weights and gaming pieces.
Archaeologists and environ-mentalists have been calling for a complete excavation of the Woodstown site since it was discovered some months ago, but until now its fate was uncertain.
The Minister, who is responsible for heritage matters, said his Department was engaged with all the relevant bodies, including the National Museum, and he had visited the site in recent weeks.
Dr Pat Wallace, the director of the National Museum, who previously led the excavation of Dublin's Wood Quay site, has made it clear that Woodstown would have to be excavated because it is so important.
Mr Cullen is expected to make an order within the next two weeks under the National Monuments Act requiring a full excavation.
All he would say was that he was working towards an outcome that would "hopefully satisfy everyone".
Asked why EU environment ministers, who were meeting in Waterford at the weekend, had not been brought to visit the site, he said there was not enough time. A tour of the Waterford Glass factory was included in their itinerary, however.
Dr Donnchadh Ó Corráin, professor of archaeology at UCC, who has been prominent in the campaign to protect Woodstown said it was "terrific" that it would be excavated and he suggested this should be done by the National Museum.
"The museum is the only truly independent institution of the State that is above reproach," he said, adding that consideration should be given to moving the proposed bypass by 100 to 150 yards to enable the excavation to proceed unhindered.
Dr Ó Corráin said the tourism potential of Woodstown, which is located in a particularly beautiful setting beside the River Suir, was "very significant" and a visitor centre should be built at the site to exhibit the archaeological finds.
Some 2,500 items have been recovered so far, mostly from the ninth century. These include Viking spears, swords, gaming pieces, weights, ship's nails and "lots of locks and keys, suggesting that large numbers of slaves were kept at the site".
Dr Ó Corráin complained that the work carried out so far was "very coarse and unscientific". It involved using a JCB to strip the topsoil and a metal detector to find items of archaeological interest. The JCB was still there at the weekend.
It is understood that only an exploratory licence was granted for Woodstown and that this licence runs out this week. "There is no excavation licence, so what is going on here is illegal," Dr Ó Corráin said on a visit to the site on Saturday.
Referring to the need for a full excavation, he said: "Mr Cullen is unlikely to be famous for a misplaced half-mile of road, but he may be famous for protecting one of the most important Viking sites to be found in western Europe."
Woodstown pre-dates the city of Waterford and was used by the Vikings as a naval base.