(Adds strategist quote and details throughout; updates prices) * Canadian dollar weakens 0.4% against the greenback * Loonie trades in a range of 1.2843 to 1.2933 * Price of U.S. oil settles nearly 2% lower * Canadian bond yields ease across a flatter curve By Fergal Smith TORONTO, Dec 22 (Reuters) - The Canadian dollar weakened for the third straight day against its U.S. counterpart on Tuesday, as fears that a new variant of the coronavirus would slow global economic recovery pressured commodity markets and bolstered the safe-haven greenback. The loonie was trading 0.4% lower at 1.2910 to the greenback, or 77.46 U.S. cents. The currency traded in a range of 1.2843 to 1.2933, after hitting a near three-week low on Monday at 1.2955. Lower oil prices and broad-based U.S. dollar strength have weighed on the loonie, "with thin pockets of liquidity" exacerbating the move, said George Davis, chief technical strategist at RBC Capital Markets. Some market participants are out before Friday"s Christmas holiday. Oil , one of Canada"s major exports, settled nearly 2% lower at $47.02 a barrel, while the U.S. dollar rallied against a basket of major currencies. Optimism about a U.S. COVID-19 relief bill that Congress passed late on Monday was tempered by concerns about the mutated coronavirus variant. Much of the world shut its borders to Britain after the new strain was discovered spreading swiftly across southern England. Canada is introducing extra measures to screen people who have spent time in Britain to check for the virus variant, Public Safety Minister Bill Blair told a briefing. A second wave of the coronavirus is sweeping across Canada. Ontario, Canada"s most-populous province, announced on Monday a partial shutdown of some businesses starting on Saturday and banned most indoor gatherings. Canadian government bond yields eased across a flatter curve in sympathy with U.S. Treasuries. The 10-year was down 2.9 basis points at 0.700%, having touched a near three-week intraday low of 0.690% on Monday. Canada"s GDP report for October is due on Wednesday. (Reporting by Fergal Smith; Editing by Kirsten Donovan and Peter Cooney)