(Adds background, market impact)
CALGARY, Alberta, July 13 (Reuters) - Syncrude Canada on Friday told buyers it would cut crude deliveries in August by about 35 percent after an outage last month at its oil sands site in northern Alberta, two market sources familiar with the matter said.
News of the reduction in deliveries tightened Canadian heavy oil differential to the narrowest in more than a month against the West Texas Intermediate (WTI) benchmark.
Canada is the world's fourth-largest oil producer and Syncrude's nameplate capacity of up to 360,000 barrels per day represents about 10 percent of the country's supply.
A power outage caused by a transformer trip last month shut the facility. Suncor Energy Inc, the biggest stakeholder in the northern Alberta project, said on Monday the site will resume some operations in July and reach full production in September.
The outage has already limited flows into Cushing, Oklahoma, the delivery point of the U.S. crude futures contract and helped tighten Canadian supplies. Inventories in Cushing last week dropped to the lowest since late 2014.
A Suncor spokeswoman did not immediately respond to a request for comment. A spokeswoman for Imperial Oil, which holds a minority stake in Syncrude, said there are no updates to the information released on Monday.
The cut in deliveries was first reported by Bloomberg. (Reporting by Devika Krishna Kumar and Rod Nickel in Calgary, Alberta; editing by Grant McCool)