A permanent bailout fund for struggling European Union economies has been agreed by government leaders in Brussels.
However, EU members have yet to agree on what those steps might be, including how it will work and what it will cost.
The BBC reports the eurozone stability mechanism will require a change to the EU's Lisbon Treaty - and that has now been agreed.
European Council president Herman Van Rompuy said EU leaders were ready to do whatever was required to protect the currency.
This year Greece and the Irish Republic have received emergency EU bailouts.
The 27 leaders agreed in Brussels on Thursday that in 2013 the permanent mechanism would succeed the eurozone's 750 billion-euro ($US1 trillion) temporary bailout fund, the European Financial Stability Facility.
But analysts say the EFSF would not be big enough to bail out Spain, if Madrid's finances deteriorated to the point where it needed a rescue.
The EFSF, which was set up in May during the Greek bailout crisis, is funded by the EU and International Monetary Fund.
Treaty changes
The BBC reports two sentences will be added to Article 136 of the Lisbon Treaty to make any future eurozone bailout legally watertight.
The new text, quoted by Mr Van Rompuy, says:
"The member states whose currency is the euro may establish a stability mechanism, to be activated if indispensable to safeguard the stability of the euro area as a whole.
"The granting of any required financial assistance under the mechanism will be made subject to strict conditionality."
"Strict conditionality" means that any eurozone country requiring such a rescue will have to tackle its debt or deficit.
Mr Van Rompuy said the treaty change can be approved through a "simplified revision procedure".
He said the aim is to put the amendment into effect by 1 January 2013 at the latest, so that the permanent fund itself can start operating in June 2013.
