"Unprincipled speculators are making billions every day by betting on a Greek default," Papandreou said on Monday, following reports US funds placed big bets against the euro.
Papandreou's trip to Washington along with George Papaconstantinou, his finance minister, with a budget deficit of 12.7 per cent of gross domestic product for 2009.
Papaconstantinou visited the International Monetary Fund in Washington to discuss technical assistance.
There has been speculation that Greece may seek an IMF bailout if support from the European Union proves inadequate. Greece has not ruled out asking the IMF for help.
Greece is planning to raise around 10 billion euros ($13.6bn) this month by issuing bonds as it races to meet debt requirements, Dow Jones Newswires reported on Tuesday citing officials.
An unnamed official said the money would be "a good cushion before the big debt maturities in April and May".
Greece needs to redeem debts of around 20 billion euros by the end of May.
The government last week sold five billion euros in 10-year bonds, but it was forced to borrow at a high rate of above six per cent - about twice the rate for a 10-year German bond - because of low investor confidence.
A second official was quoted in the report as saying: "We still expect some kind of an arrangement from the European Union ... There are discussions on this matter so that Greece can pay more logical yields."