The euro eased on Monday after making significant gains, with many investors wary of buying the currency on caution about how effective action pledged by European policymakers to resolve the euro zone crisis would be. 

The euro earlier hit a one-month high against the dollar, adding to Friday's gains on investor optimism the European Central Bank would step in and buy bonds to reduce high Spanish and Italian borrowing costs in coming months.

 

But analysts said uncertainties remained over the ECB's plan and many saw more pain for the euro zone before a resolution to the crisis was reached. This meant some investors were inclined to use the euro's bounce to put on fresh bets the currency would weaken.