PRECIOUS-Gold steady below $1,660; platinum, palladium shine

* Asia's physical demand slows as prices stagnate

* Gold-platinum ratio hits nine-month high; may further rise

* Spot gold may retrace to $1,642.14/oz - technicals

* Coming up: ECB rate decision, 1245 GMT

(Adds comments and details; updates prices) SINGAPORE, Jan 10 (Reuters) - Gold edged up on Thursday, with investors eying a key resistance level just above $1,660 an ounce and awaiting a rate decision by the European Central Bank at its policy meeting later in the day. Platinum group metals, encouraged by an improving economic outlook on better-than-expected trade data from China, stole the show, with spot platinum rising to a three-week high and spot palladium on course for a third day of rises. The ECB is expected to hold interest rates unchanged, but economists have mixed views on the chances of a rate cut in the next few months due to a murky economic outlook.

Central banks' monetary stimulus was a key driver behind gold's twelfth year of annual gains in 2012, as investors concerned about the side effects of rampant cash printing fled to bullion to hedge against inflation. Gold has been moving in a narrow range of about $25 this week, with the upside capped by signs that the United States might end its easy money policy. Physical buying in Asia has helped support prices above $1,640 an ounce. Gold dropped to a more than four-month low below $1,630 an ounce last week after minutes from the U.S. Federal Reserve's last meeting showed officials were concerned about the side effects of its bond-buying programme. "The market got a little concerned about how aggressive the Fed will be," said Jeremy Friesen, commodity strategist at Societe Generale in Hong Kong, adding that the market is expected to rebound. SocGen expected gold to average $1,700 an ounce in the first quarter of the year, as well as for all of 2013. Spot gold inched up to $1,659.04 an ounce by 0747 GMT, below the key resistance of the 200-day moving average at $1.661.07. U.S. gold rose 0.2 percent to $1,659.50 an ounce. Technical analysis suggested that spot gold could retrace to $1,642.14 an ounce during the day, said Reuters market analyst Wang Tao.

The dollar index inched higher, on course for its third day of gains. A stronger greenback makes dollar-priced commodities less affordable for buyers holding other currencies.

Robust purchases on the physical bullion market in Asia were showing signs of slowing down, after prices settled in a range, dealers said. "Prices have been at the current level for a week or so, and we will see some slowdown in physical buying, unless prices go down to $1,640 or $1,650," said a Singapore-based trader.

PLATINUM GROUP METALS FIRM Spot platinum gained 1.1 percent to $1,608.50 an ounce. It rose to a three-week high of $1,614 earlier. The gold-platinum ratio rose to near 0.97, its highest in nine months "Platinum fell the most last year. Given people believe in a U.S. economic recovery, industrial metals should outperform gold and we should see platinum prices move above gold again," said a second Singapore-based trader. Spot palladium gained nearly 2 percent to $696.50, easing from a one-week high of $709 an ounce earlier.

Precious metals prices 0747 GMT

Metal Last Change Pct chg YTD pct chg Volume Spot Gold 1659.04 1.75 +0.11 -0.93 Spot Silver 30.39 0.06 +0.20 0.36 Spot Platinum 1608.50 17.50 +1.10 4.79 Spot Palladium 696.50 13.40 +1.96 0.65 COMEX GOLD FEB3 1659.50 4.00 +0.24 -0.97 12918 COMEX SILVER MAR3 30.41 0.16 +0.53 0.60 4508 Euro/Dollar 1.3070 Dollar/Yen 88.23

COMEX gold and silver contracts show the most active months

(Editing by Muralikumar Anantharaman)