Talisman has a number of operations in Scotland

The leak was found in a pipeline carrying supplies from Beatrice - which pumps out �500,000 of oil a week - to the shore.

Talisman's John MacDonald said that the problem was probably due to wear and tear.

But he said that the leak was "minimal" and did not lead to an oil-slick. The pipeline has now been cleared of its oil and flushed with seawater.

He added: "Further tests are being carried out to assess the integrity of the line and provide data to determine the best method of repair or replacement.

"Such an assessment is unlikely to be completed before the end of the year. The field will not be back on line before April 2001."

I can hardly believe that this is the only pipeline in the North Sea which is no longer up to the task

Lang Banks, Friends of the Earth Scotland

He stressed that the firm would not start pumping oil through it again until it was certain that there were no risks.

Only a handful of the 40 or 50 crew members who usually manned the main steel platform main steel platform were left on board carrying out essential maintenance.

The remaining workers have been deployed on the company's other North Sea fields.

Friends of the Earth Scotland's Lang Banks called on other oil companies to step up their monitoring programmes in the light of the leak.

"I can hardly believe that this is the only pipeline in the North Sea which is no longer up to the task," claimed the environmentalist.

In March, Talisman started drilling for oil in the Moray Firth's Marcel Field - closer to the shore than any other oil development.

The company predicted it would prolong the life of the Nigg oil terminal on the Cromarty Firth if it found oil.