* Yen gains as geopolitical worries increase
* Euro-yen sinks for 11th straight day, touches lowest since Nov
* French presidential election also weighs (Updates to U.S. afternoon trading, adds data, quote)
By Dion Rabouin
NEW YORK, April 11 (Reuters) - The dollar fell broadly on Tuesday, nearly touching a five-month low against the Japanese yen, as geopolitical risk and declining U.S. Treasury yields pushed traders out of the greenback.
The yen gained across the board on concerns about Syria and North Korea, and a resurgence of a previously written-off left-wing contender in France's presidential race further prompted buying of the safe-haven currency.
"It shows how nervous markets are about the geopolitical situation," said Marc Chandler, global head of currency strategy at Brown Brothers Harriman. "And at the end of the day the focus on the geopolitical data is coming without much serious economic data."
U.S. Treasury yields fell for a second straight day as anxiety increased.
The yen rose in what analysts called a "knee-jerk reaction" after Reuters reported black smoke rising from part of an airfield in Moscow. The smoke turned out to be caused by grass and refuse burning nearby.
That move pushed the dollar through the key technical level of 110 yen, prompting a reversal of many positions.
"Taking (the news) in conjunction with what looks to be limited liquidity conditions in the holiday-shortened week leaves this pair and the market more generally very prone to large moves," said Mazen Issa, senior FX strategist at TD Securities.
The dollar fell more than 1 percent against the yen and was last trading at 109.67 yen, its lowest since Nov. 17.
The euro also fell 1 percent against the yen as investors weighed the possibility of a face-off between far-right candidate Marine Le Pen and hard-left candidate Jean-Luc Melenchon, who has surged in polls recently.
Pledges by Le Pen and Melenchon to hold referendums on France's membership in the European Union have sparked fears among investors of the potential for a wider breakup of the euro zone.
The single currency suffered its 11th straight day of declines against the yen; it was the longest streak in the history of the euro, Chandler noted. The euro fell to 116.31 yen, the lowest since Nov. 17.
The dollar index, which gauges the U.S. currency against a basket of six major peers, was off 0.3 percent on the day at 100.71. (Reporting by Dion Rabouin; Additional reporting by Ritvik Carvalho; Editing by Dan Grebler and Steve Orlofsky)