Shell, one of the world's largest oil and gas companies, has said it will continue to pursue the Corrib gas field project despite a protracted planning process and opposition from local groups in Co Mayo.

A statement released yesterday by its Irish subsidiary, Enterprise Energy Ireland, said it would not be switching its focus to operations away from the Corrib. The statement said the company fully respected the An Bord Pleanála planning process currently under way and was awaiting a decision from the board.

Some weekend reports suggested the company was planning to switch its focus to Mexico if planning permission came with a plethora of conditions. The company strongly denied this in the statement.

"In any event, the terms of Enterprise Energy Ireland's petroleum lease requires, subject to planning permission and regulatory approvals, that the Corrib gas field be developed or the licence handed back to the State," said the statement.

The company said it had invested over € 200 million since 1996 on Corrib and this was another reason for sticking with the process. In a further demonstration of its commitment, said the statement, resumed drilling operations on its Dooish prospect, 150 kilometres off-shore Donegal would begin in early May.

The Corrib field is the second largest gas find made in Irish waters.

An investment of about €800 million will be needed to bring the gas ashore. The task is made difficult because the gas is located 349 metres below sea level.

A determined campaign against the project has been mounted by local groups. Some claim the project could damage local scenic areas, while others have warned that fish stocks could be threatened.

An Bord Pleanala were due to make a decision on Corrib earlier this month, but they have decided to take more time.