UPDATE 1-Suncor fixes Alberta oil sands processing unit

(Adds details)

CALGARY, Alberta, Oct 9 (Reuters) - Suncor Energy Inc SU.TO said on Thursday it finished repairs to a processing unit at its Alberta oil sands plant shut down since August and had begun startup preparations.

The shutdown of the hydrotreater at Suncor’s oil sands upgrader north of Fort McMurray, Alberta, did not affect overall production levels, but cut its ability to produce light, synthetic oil and diesel fuel, the company said.

The outage has been cited as one reason for a shortage of diesel in Western Canada. Supplies of the transport fuel have also tightened due to work at Edmonton-area refineries run by Petro-Canada PCA.TO and Imperial Oil Ltd IMO.TO.

Suncor did not say in a statement how long it will take for the unit -- which supplies some of the hydrogen used to remove sulfur from the heavy crude wrung from the oil sands -- to be back in full operation.

The company said it produced 235,000 barrels a day in September from its oil sands facility, which is Canada’s second-largest. It is targeting average output of 240,000-250,000 barrels a day in 2008. (Reporting by Jeffrey Jones; editing by Rob Wilson)