The euro was at $1.3814, little changed over the past few sessions. It hit a 2-1/2 year high near $1.40 last month, and since then European Central Bank officials have tried to talk it down given concerns that a strong currency could derail the euro zone's fragile economic recovery.
The latest was Executive Board member Yves Mersch, who said a sustained appreciation in the euro would inevitably trigger a reaction from the ECB.
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Last weekend, ECB President Mario Draghi identified the euro's strength as a possible trigger for easing policy.
"The euro, if given the chance, tends to rise. The only really effective measure to counter the currency's strength would be quantitative easing," said Masafumi Yamamoto, market strategist at Praevidentia Strategy in Tokyo.
"The ECB will want see the European Supreme Court approve the Outright Monetary Transactions first before it adopts quantitative easing. This may not take place until September at the earliest, and it will likely try to buy time until then."
Outright Monetary Transactions (OMT) is the ECB's as-yet-unused "unlimited" bond-buying scheme, its flagship emergency measure against the euro zone's debt crisis.
The German court took the unprecedented decision in February to defer the ruling regarding the OMT's legality to the European Court of Justice in Strasbourg.
Sterling hit 4 1/2-year high of $1.6842 on Thursday, after better-than-expected UK jobless data bolstered expectations the Bank of England may have to raise interest rates earlier than its peers. On Friday it had eased back to $1.6785.