They include BP, Shell, British Gas, Enterprise Oil and British Borneo, which were among 17 companies applying for the "frontier" blocks, which the Irish government put on offer last year.

Norwegian and US companies were also included in the list of successful applications announced by Emmet Stagg, Ireland's minister for transport, energy and communications. He described the response as "excellent" with several blocks attracting competing bids.

He told a press conference in Dublin that the confidence shown in the unexplored areas with significant prospects augured well for the future of the country as a potential oil and gas producer. "I think that it would be fair to say that the Rockall Trough is emerging as one of the most exciting untested areas in north-west Europe," he said. Although the applications only required companies to propose work programmes for seismic surveys during the first phase of operations in water depths to 7,500 feet, Mr Stagg said that one group had made a commitment to drill a well and another two had allocated funds in their first-phase budgets which could be used for drilling if promising prospects are identified by the seismic work.

The awards mean the resumption of Irish exploration by BP and Shell, which both relinquished previous interests in other parts of the Irish continental shelf after failing to make any finds which were considered worthwhile during the 1970s and 1980s.

The two groups will be working in the Rockall Trough in partnership with Norway's Statoil which last year took up a block given up by BP.

Enterprise Oil is among partners awarded a licence covering four full and two part exploration blocks in the new deep-water areas. BG, which also abandoned its Irish drilling interests in 1991, is a partner in two groups awarded a total of seven full and two half blocks while British Borneo will be in-volved in exploration covering two full and one part block.