Negotiations between the IDA and Dell have been underway since August and the deal - which was being finalised last night - has been on and off on several occasions.

On foot of soaring sales figures, Dell has been seeking to expand its manufacturing capacity for at least six months and, according to sources, was open to offers involving suitable sites which could be put into operation almost immediately.

The IDA became aware of this last August and when news of the impending closure of the Seagate plant in Clonmel was announced in December and doubts emerged over the future the Samsung-owed AST plant in Limerick just before Christmas, both sites were advanced to Dell as potential locations.

The company chairman and chief executive, Mr Michael Dell, was personally informed that either location might be suitable.

Several meetings took place between IDA representatives and Mr Dell in the United States and he is said to have conducted much of the negotiations personally.

One source said last night that his stance in the discussions was that Ireland was his preferred option, but he wanted the case "proven to him".

The strongest competition facing the IDA came from its British industrial counterparts who suggested several sites in Scotland.

The Tanaiste and Minister for Enterprise, Trade and Employment, Ms Harney, had several lengthy telephone conversations with Mr Dell. These discussions were said to have intensified after the announcement that Seagate would close. Mr Dell was assured by Ms Harney that adequate numbers of skilled workers would be available to Dell.

The main elements of the deal were agreed last week and Mr Dell approved the final round of negotiations which were continuing last night.

Mr Dell was not in Dublin yesterday for the last phase of bargaining but he is said to have been in close contact throughout.