Shell says unplanned outage cuts St Fergus gas terminal flows

LONDON, Sept 16 (Reuters) - An unplanned outage has cut gasflows at Shell's St Fergus gas processing terminal,Shell said on Tuesday.

"Some minor unplanned maintenance work has temporarilyimpacted gas flows to St Fergus. We expect levels to return tonormal shortly," a spokeswoman for the company said.

National Grid data showed volumes fell to zero early onTuesday morning from more than 20 mcm/day on Monday evening.By 1330 GMT volumes were still zero, the data showed.

Shell said on its website late on Monday it had extended a12 mcm/day capacity reduction at St Fergus until the weekcommencing Sept. 29, but the firm's website did not flag up onTuesday the unplanned drop in volume to zero.

The unplanned maintenance contributed to an undersuppliedsystem in Britian's gas market on Tuesday morning, sendingprompt prices higher. (Reporting By Susanna Twidale; editing by David Clarke)