* March WCS quoted at $26.75/bbl under WTI * March synthetic $0.65/bbl over WTI * Apportionment eases, Kearl start-up pushed back CALGARY, Alberta, Feb 6 (Reuters) - Canadian heavy crude prices climbed to their highest point in 12 weeks on Wednesday on the back of reduced pipeline congestion and speculation that some players may have been caught short, trading sources said. Western Canada Select heavy blend for March delivery last sold for $26.75 a barrel under benchmark West Texas Intermediate, compared with a Tuesday settlement of $28.75 a barrel under, according to Shorcan Energy Brokers. That was its narrowest differential since Nov. 12. Traders said they were surprised by this month's steady gains, which come after two months of discounts that at times topped $40 a barrel. Surging production, tight pipeline capacity and a series of refinery outages have been blamed for the slump. Some of the recent strength is the result of "most likely, some guys having to cover losses," one marketer said. Apportionment levels on Enbridge Inc's pipeline network to the U.S. Midwest are below those set for last month, easing some of the price pressure, traders have said. The company put single-digit restrictions on Line 5, 4 and 67, and 21 percent apportionment on Line 6B. Last month Enbridge imposed a rare mid-month apportionment. In addition, the start-up of Imperial's 110,000 barrel a day Kearl project in northern Alberta, first expected to begin commercial production at the end of 2012, is now targeted for the end of the first quarter. Full production is scheduled for the "next several months". Light synthetic crude prices also strengthened on Wednesday after Suncor Energy Inc and Syncrude Canada reported lower oil sands-derived crude production for January. March light synthetic last sold for 65 cents above WTI, compared with a discount of 35 cents on Tuesday.