The dollar firmed up against key European currencies on Tuesday, supported by renewed fears that the Greek debt crisis may spread to other vulnerable European states.

Greek officials visiting Washington downplayed their nation's role in driving down the value of the euro, blaming the crisis on speculators betting Athens will default on its bond payments.

Prime Minister George Papandreou met with U.S. President Barack Obama on Tuesday, urging stronger regulation of the hedge funds and currency traders that have made massive bets against Greece and the euro.

Papandreou stressed on Monday the U.S. must play a vital role in stopping "unprincipled speculators" from aggravating the Greek debt problems and doing further damage to already frail global financial markets.

The dollar improved to 1.3550 versus the euro, edging back toward last week's 9-month high of 1.3434.

The buck also rose versus the sterling, rebounding to 1.5000. With the advance, the buck moved closer to last week's 9-month high near 1.4800.

Credit rating agency Moody's Investors Service said Tuesday it may cut its ratings on some U.K. banks in the medium term as the government winds down its support measures.

On the flip side, the dollar continued a slump toward parity versus its Canadian counterpart. The buck hit C$1.0234, and a move below C$1.0200 will take the buck to its lowest since August 2008.

The bucked came under modest pressure versus the yen, easing back below Y90.

Looking ahead to later in the week, traders will be treated to US figures on retail sales and initial jobless claims, as well as Wednesday's wholesale inventories data.