"(The ECB) may undertake outright open market operations of a size adequate to reach its objective," ECB President Mario Draghi said at the much-awaited press conference at Frankfurt.
The details of the operations to help Spain and Italy to raise funds at competitive rates would be worked out in the coming weeks, he added.
Replying to questions on the future of European currency, Draghi said, "the euro is irreversible."
A few weeks ago, there were widespread fears that the 17- nation currency would collapse as more countries like Spain came under the European sovereign debt crisis.
Earlier in the day, the ECB announced its decision to keep the benchmark interest rate unchanged at 0.75 per cent disappointing the bond market that was expecting some concrete steps as promised by Draghi earlier.
The ECB chief last week had promised to take steps to save euro and intervene in the market to push down the borrowing costs for debt-ridden European countries.
The stocks in Spain plummeted more than 5 per cent in absence of specific ECB announcements for bringing down the borrowing cost. (MORE)