European Central Bank head Mario Draghi opened the door for further stimulus on Thursday, saying the bank is preparing the technical groundwork for new support measures that it can deploy if needed. Stocks rallied and the euro slumped on the news.

The ECB did not announce any new monetary support after its governing council meeting Thursday, at which it left its key interest rate at a record low of 0.05 percent.

But Draghi's comments on the preparations for more measures jolted markets.

The euro fell to $1.2394 from $1.2520 before Draghi started speaking. It is the first time it has traded below $1.24 since August 2012, when Draghi famously promised to do "Whatever it takes" to save the euro. Central bank stimulus measures can weigh on a currency.

In stock markets, Germany's DAX index jumped 1.4 percent.

Draghi has said the ECB could — if the economy worsens — offer more monetary support, such as large-scale bond purchases to pump newly created money into the economy. Such a program, called quantitative easing, or QE, has been used with some success by the U.S. Federal Reserve.

But the ECB has held off, in part because of skepticism about the measure in Germany, the eurozone's largest and most influential member.

The ECB also wants to give an opportunity to measures it is already deployed to start having an effect. The ECB this summer slashed its benchmark interest rate, offered cheap loans to banks, and started purchasing bonds backed by bank loans. All are steps aimed at easing credit to companies.

On Thursday, however, Draghi indicated the ECB would be ready to offer more help to the economy if required. He said the 24 member governing council has tasked staff "with ensuring the timely preparation of further measures to be implemented, if needed."

Draghi also repeated a comment from the October meeting that the ECB was aiming to raise its balance sheet of holdings — one measure of the size of its overall stimulus efforts — toward the size it had in 2012, when it reached 3 trillion euros ($3.8 trillion). It subsequently fell toward 2 trillion euros as banks repaid earlier rounds of ultra-cheap loans.

By stressing that the governing council supported his statements, Draghi appeared to be responding to news media reports that a large minority on the council opposed QE and was angry at Draghi for giving the vague balance sheet target.

Draghi said the council had examined the experience of other central banks including the Fed, Bank of Japan, and Bank of England, all three of which have done QE. He said that there was "profound diversity of situations" in each economy, and that "the effects of QE are different depending on the initial conditions."

He added that other banks' experiences "are very important in that they make us think how to make the most of the measures that we may be taking, if needed."