* Commodity currencies lead fresh round of dollar selling * Sterling on edge heading in to crucial Brexit weekend * Graphic: World FX rates in 2020 tmsnrt.rs/2RBWI5E By Tom Westbrook SINGAPORE, Dec 11 (Reuters) - The dollar headed for a fourth weekly loss in a row on Friday to languish in multi-year troughs against other majors, and sterling snapped a five-week winning streak after British and European leaders remained far apart on a post-Brexit trade deal. The greenback is pinned near a two-and-a-half year low against a basket of currencies as investors bet on better returns in other currencies as the pandemic recovery takes hold. On Friday, commodity currencies led the charge. Surging iron ore prices lifted the Australian dollar to a two-and-a-half year high of $0.7572 and a weekly gain of 1.8%. A nine-month peak for oil prices pushed the Canadian dollar to its highest since 2018 and the kiwi broached 71 cents to hit $0.7112, also its strongest since 2018. "The Aussie can do no wrong when the commodity price backdrop just goes from strength to strength," said Ray Attrill, head of foreign exchange at National Australia Bank in Sydney. "Whether you want to look at it through the prism of ongoing dollar weakness or the acceleration in key commodity prices...it"s hard to fight it," he said. Australian dollar crosses also leapt to new peaks, with the Aussie at a one-and-a-half year high against the yen, a six-month peak on the euro, a three month top against the yuan and a three-week high on the kiwi . The euro rose against the dollar to $1.2160 after the European Central Bank delivered no surprises on Thursday and regional leaders reached a compromise with Hungary and Poland over a pandemic aid package. The common currency has soared 15% from three-year lows at the height of the March markets panic and has added nearly 2% in two weeks since finally breaking $1.20 after multiple attempts. "With the strong bearish dollar dynamics in place, the trend in EUR/USD is up," said Peter Krpata, a currency strategist at Dutch bank ING. "We target $1.25 in 2021, with strong upside risks to $1.30." WEEKEND AT BRUSSELS Sterling was an outlier ahead of a weekend of brinkmanship, as British and EU negotiators have been told they have until the end of Sunday to decide whether a trade deal is possible. It has slipped 0.9% this week as British and European leaders have expressed doubts that they will be able to salvage a deal. At $1.3309, it is still priced for a deal that averts tariffs and quotas being imposed on some $1 trillion in annual trade from January 1. But options market moves show traders bracing for chaos, with one-week implied volatility at a new eight-month high and the premium of sterling puts to calls near its highest since April as investors pay up for downside protection. Sterling has fallen three weeks in a row against the euro and was steady at 91.31 pence in Asia after falling on Thursday. "With financial markets having bought sterling for months on the assumption a Brexit trade deal would be completed, the risk is that may have been a false hope," said Jeffrey Halley, senior analyst at currency broker OANDA. "I sense that the market is still clinging to that conviction and has not yet materially thrown in the towel," he said. "That could well change on Sunday, meaning that Monday morning in Wellington, New Zealand, when currency markets open in the wee hours, could be emotional." ======================================================== Currency bid prices at 1:44PM (544 GMT) Description RIC Last U.S. Close Pct Change YTD Pct High Bid Low Bid Previous Change Session Euro/Dollar $1.2155 $1.2142 +0.10% +8.42% +1.2160 +1.2140 Dollar/Yen 104.0100 104.1850 -0.17% -4.24% +104.2650 +103.9400 Euro/Yen 126.41 126.51 -0.08% +3.66% +126.6100 +126.2800 Dollar/Swiss 0.8856 0.8858 -0.02% -8.47% +0.8862 +0.8854 Sterling/Dollar 1.3310 1.3293 +0.12% +0.35% +1.3323 +1.3293 Dollar/Canadian 1.2728 1.2742 -0.11% -2.02% +1.2747 +1.2723 Aussie/Dollar 0.7558 0.7536 +0.30% +7.72% +0.7572 +0.7523 NZ 0.7097 0.7100 -0.06% +5.45% +0.7112 +0.7090 Dollar/Dollar All spots Tokyo spots Europe spots Volatilities Tokyo Forex market info from BOJ (Reporting by Tom Westbrook; Editing by Ana Nicolaci da Costa)