* Graphic: World FX rates in 2019 http://tmsnrt.rs/2egbfVh
By Daniel Leussink
TOKYO, April 23 (Reuters) - The dollar edged up against abasket of key rivals on Tuesday, while the Canadian dollar wassupported by rising crude oil prices due to U.S. plans totighten a clampdown on Iranian oil exports from next month.
The dollar index against a basket of six key rivals was ashade higher at 97.336 .DXY , edging toward the 2019 high of97.71 struck in early March.
The greenback has firmed in recent weeks on the back ofhigher U.S. 10-year Treasury yields US10YT=RR and signs ofstrength in the U.S. economy following a weak start of the year.
Data released overnight showed U.S. existing home sales fellmore than expected in March amid supply constraints, and figuresfor new home sales will be released later in the globalday. urn:newsml:reuters.com:*:nL1N2240DI
While those may provide some pointers to the state of theU.S. economy, a clearer picture should emerge from the grossdomestic product report set for release on Friday.
"Investors will be looking for an increase in volatility inthe days ahead as traders return to desks and earnings season inthe U.S. steps up," said Nick Twidale, chief operating officerat Rakuten Securities Australia in Sydney.
"This week could give a strong indication of whether thedramatic dovish turn from global central banks, and inparticular the Fed, over the last few months has been enough tochange the global growth dynamic," he said in a note.
Against the yen, the dollar gave up a tenth of a percent to111.80 yen JPY= , moving off a high for this year of 112.17 hitlast Wednesday, while holding above its 200-day moving average.
Masafumi Yamamoto, chief currency strategist at MizuhoSecurities, said he did not see a strong driver for thegreenback's fall. He added the move could have been triggered bya risk-off tone in the Japanese equity market.
Yamamoto expected the yen's strength against the dollar tobe temporary as long as central banks around the world refrainfrom normalising policy through raising interest rates.
"The relative dovish tone of the central banks is supportingrisk assets," he said. "That's why dollar/yen has been supportedby risk on trading. I think this kind of move will continue aslong as major central banks make no move for a while."
The Australian dollar drifted 0.1 percent lower to $0.7128percent AUD=D4 ahead of the release of first-quarter inflationdata due on Wednesday.
The greenback's moves against the euro and sterling weresmall, with the single currency slightly lower at $1.1249EUR= and the pound up a tad at $1.2985GBP=D4 .
The Canadian dollar held firm after oil prices rallied tonear six-month highs overnight on news that Washington plans toeliminate waivers next month for eight countries to buy Iranianoil without facing U.S. sanctions. urn:newsml:reuters.com:*:nL3N22404Iurn:newsml:reuters.com:*:nL1N224079
With the jump in the price of oil, one of Canada's majorexports, the loonie was down slightly at $0.7485CADUSD=R ,holding most of the previous session's gains of over a third ofa percent.
(Editing by Simon Cameron-Moore & Kim Coghill) ((firstname.lastname@example.org; Twitter: @danielleussink;+81-3-6441-1825; Reuters Messaging:email@example.com))