UPDATE 1-Shell says boosting output at Canadian refinery

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CALGARY, Alberta, May 15 (Reuters) - Royal Dutch Shell Plc (RDSa.L: Quote, Profile, Research, Stock Buzz) said on Thursday it is increasing production at its 72,000 barrel a day Sarnia, Ontario, refinery after a week of unplanned maintenance on one of the units.

The plant, the smallest of Shell's three refineries in Canada, should be back at full rates soon, spokesman John Peck said, without elaborating.

"It's being restarted," Peck said.

He declined to say which unit was down for repairs or by how much output was reduced during the work.

The impact of the outage on Shell's Ontario retail network has not been large, he said.

"There have been very few total run-outs of gasoline, only 1 or 2 percent," Peck said. (Reporting by Jeffrey Jones; Editing by Peter Galloway)