* Euro falls most vs dollar since November on euro-zone debt * S&P revises U.S. long-term rating outlook to 'negative' * Newspaper says Greece asked IMF/EU to restructure debt * Finnish vote result sparks uncertainty about Portugal (Updates prices, adds quotes)
By Julie Haviv
NEW YORK, April 18 (Reuters) - The euro slid more than 1 percent against the dollar on Monday, suffering its worst one-day drop since November on mounting concerns that Greece will be forced to restructure its debt.
Another factor hurting the euro was anti-aid sentiment in Europe, which showed signs of growing.
Rampant risk aversion generally weighed on the euro zone's single currency even as Standard & Poor's revised its outlook on the United States' long-term rating to negative from stable but affirmed its 'AAA/A-1+' sovereign credit rating.
An actual ratings downgrade of U.S. debt would be negative for the U.S. dollar, but most believe S&P's announcement was a warning and therefore, it did little to rattle the greenback's performance against the euro.
In late afternoon New York trading. the euro was down 1.4 percent at $1.4232, with the session low at $1.4155 -- a two-week low -- according to Reuters data. It was the biggest fall since a 1.86 percent decline on Nov. 23.
The euro's rise has stalled since it hit a 15-month high last week.
"The key takeaway from the S&P announcement is that the U.S. has been put on notice, but no ratings action is likely until 2013," said Win Thin, global head of emerging markets strategy at Brown Brothers Harriman in New York.
"With no one expecting any serious progress on deficit reduction until after the 2012 election, S&P seems to be simply firing a shot across the bow to U.S. policymakers," he said.
While U.S. fiscal tensions are increasing, the United States is far from defaulting on its debt.
"Continued concerns about America's bloated deficits and policymakers' inability to agree on the difficult measures needed to address budgetary challenges remains a key risk for the dollar," said Omer Esiner, chief market analyst at Commonwealth Foreign Exchange in Washington.
Esiner said while this is remote, the risk may be increasing.
The possibility of the U.S. losing its AAA rating could result in a wholesale abandonment of dollar assets and would potentially destabilize the entire global economy, he said.
German government sources said they expected Greece will not make it through the summer without debt restructuring, although Athens denied a debt rescheduling was imminent.
Earlier, a Greek newspaper reported that Greece had told the IMF and the European Union this month it wants to restructure its debt. Greek debt pared losses as a finance ministry source in Athens said the story was untrue.
Players also monitored Portugal's progress toward a bailout after strong gains in a weekend election in Finland by an anti-euro party that has vowed to veto the rescue package.
Analysts doubted the Finnish vote could do more than slow down a bailout, but the vote's outcome added to negative euro sentiment, encouraging investors to cut long positions.
"The real fear is that anti-euro aid sentiment is building across Europe, which, should it spill into countries like Germany, could have significant ramifications," said Camilla Sutton, chief currency strategist at Scotia Capital in Toronto.
FOR U.S., A NEGATIVE OUTLOOK
Standard & Poor's cited huge budget deficits and rising government indebtedness as the reason for the U.S. outlook revision, with the path to addressing those issues unclear.
The euro fell to its lowest in almost three weeks against the yen. It last traded at 117.60 yen, down 1.9 percent.
The dollar also hit its lowest in almost three weeks against the yen to around 82.16 yen, before recovering to 82.62 yen, down 0.6 percent for the day.
"In jittery markets and given plenty of event risk, the clearest winners look to be the Swiss franc and Japanese yen, which should remain well supported during the next 24 to 48 hours," said Nick Bennenbroek, head of currency strategy at Wells Fargo in New York. (Reporting by Julie Haviv; Additional reporting by Nick Olivari; Editing by Jan Paschal)