* Euro down 0.5 percent vs dollar at $1.3675
* Single currency hit by reported Greek comments
* Risk demand dwindles, high-risk FX edge lower
(Adds comment, details, updates prices)
By Neal Armstrong
LONDON, March 18 (Reuters) - The euro fell on Thursday after a media report saying Greece is not hopeful of receiving aid from euro zone members added to uncertainty over a resolution to its debt problems and soured sentiment for the single currency .
An unidentified Greek official quoted in the report said Greece was increasingly pessimistic about the prospect of help at a March 25 European Union summit and may seek International Monetary Fund aid during the April 2-4 Easter weekend.
Greece, battling to deal with crippling debts, has said it is counting on EU leaders to approve a mechanism to help the country at next week's meeting.
But some countries -- especially Germany, the EU's biggest paymaster -- are wary of making concrete promises, and analysts said the Dow Jones Newswires report suggested a rift between Greece and Germany may be deepening.
"This just highlights the uncertainty surrounding the Greece issue. There seems to be no consensus in the euro zone, which is undermining confidence and that is what is weighing on the euro today," said Antje Praefcke, currency strategist at Commerzbank.
Comments from German Chancellor Angela Merkel, who said on Wednesday the Greek crisis had landed the euro with its biggest challenge, were also putting selling pressure on the single currency.
At 1044 GMT, the euro was down around 0.5 percent on the day to $1.3675, pulling back from a five-week high of $1.3819 hit on electronic trading platform EBS on Wednesday.
The euro struggled as European shares retreated from a 17-month closing high hit on Wednesday, while prices for oil, another risky asset, fell 0.5 percent on the day.
Analysts said the latest news about Greece had cooled demand for higher-risk assets, including currencies. "The market has been trying to chase risk all week and (the Greek comments) are a reality check," said Geoffrey Yu, currency strategist at UBS in London.
The euro hit the day's low around $1.3650 in early European trade, but losses were limited due to suspected demand from Asian central banks around that level, traders said, while trendline support around $1.3640 also prevented more losses. Some technical analysts said a break under that level may open the door to a fall to around $1.3405, the 61.8 percent Fibonacci retracement of the euro's rise from its 2008 low around $1.23 to its highest of 2009 around $1.50.
DOLLAR GAINS
The dollar rose 0.4 percent against a basket of currencies to 79.959. The greenback slipped 0.2 percent to 90.10 yen as the Japanese currency benefited from risk aversion, pushing the euro down 0.6 percent to 123.30 yen.
Versus the Canadian dollar, the U.S. dollar pulled back from a 20-month low of C$1.0071 hit on Wednesday to trade at C$1.0108, but analysts see the pair hitting parity in the near term on speculation that Canadian interest rates may soon rise.
Analysts said escalating tensions between the United States and China over Beijing's yuan policy also remained on traders' radars and may provide more support to the dollar.
The spat between Washington and Beijing has turned acrimonious, with 130 U.S. lawmakers demanding sanctions unless China gives up what they see as an unfair competitive advantage by allowing the yuan to appreciate.
Investors awaited the latest U.S. consumer inflation data later in the day, along with initial jobless claims and the Philadelphia Federal Reserve Business Activity survey.
(Additional reporting by Naomi Tajitsu; Editing by Nigel Stephenson)