The euro touched an eleven-year low against the dollar overnight after anti-austerity party Syriza swept to victory in Greece's general election, sparking fears of an exit from the euro zone.

The common currency was trading at $1.1278 after dipping to $1.1088 in Tokyo early morning trade, the lowest level since September 2003.

The euro had tumbled to an eleven-year low of $1.1115 in New York on Friday, after the European Central Bank unveiled a vast bond-buying programme to try to kickstart the struggling euro zone economy.

The unit also fell to 131.39 yen today in Tokyo against 132.03 yen, while it slipped to 0.9833 against the Swiss franc, from 0.9876 on Friday.

Leftist party Syriza pulled off a historic win in Greece's election Sunday, becoming the first anti-austerity party in power in Europe.

The victory presents a new challenge to the debt-hit country's international bailout programme and has ignited fears about the possibility of Greece exiting from the euro zone.

"The drop in the euro-dollar certainly reflects fears over the euro zone economy stirred by the Greek election," said Marito Ueda, senior dealer at FX Prime.

The euro rose later as traders had factored in the impact to some extent in advance, "but you might want to be careful about the further developments -- the euro will remain top-heavy", Ueda said.

Syriza took over 36% of the vote compared to 28% for the conservative New Democracy party of incumbent Prime Minister Antonis Samaras, with more than half of ballots counted.

Syriza's leader Alexis Tsipras vowed to renegotiate the terms of Greece's €240bn bailout with the European Union and the International Monetary Fund.

The possibility of Greece defaulting on its debt repayments has stoked concern it could be forced to leave the euro zone.

But some analysts threw cold water on the prospect.

"We still think Greece will stay within the euro zone," Elsa Lignos, a senior currency strategist at RBC Capital Markets, said in a note.

"Ultimately we think an anti-bailout is unlikely to last through the summer. Greece will stay within the euro area, which coupled with a euro-area economic recovery in the second half of the year, would give the euro a V-shaped profile for 2015."

In other trading the dollar fetched 117.88 yen against 117.80 yen on Friday, while the Australian dollar dropped to 78.80 US cents. That was the lowest level since July 2009, which National Australia Bank attributed to weak metal prices hurting the resource-driven economy. 

The Aussie had fallen below 80 cents on Friday for the first time since mid-2009 before ticking back up to 80.63 cents.

The dollar was mixed against other Asia-Pacific currencies.

It slipped to 44.11 Philippine pesos from 44.14 pesos on Friday, to 1,079.53 South Korean won from 1,084.43 won, to Tw$31.29 from Tw$32.31, and to 32.58 Thai baht from 32.60 baht.

The greenback strengthened to 12,510.00 Indonesian rupiah from 12,471.00 rupiah and to Sg$1.3454 from Sg$1.3339, while it was flat at 61.43 Indian rupees.

The Chinese yuan fetched 18.82 yen, down from 19.05 yen.