The European Central Bank (ECB) announced a massive new bond-buying program Thursday in a bid to stimulate the ailing euro zone economy.

The central bank's quantitative easing (QE) program will entail 20 billion euros ($21.9 billion) per month of net asset purchases for as long as it deems necessary.

The ECB also cut its main deposit rate by 10 basis points to -0.5%, a record low but in line with market expectations.

It now expects interest rates to remain at their present or lower levels until it has seen its inflation outlook "robustly converge to a level sufficiently close to but below 2% within its projection horizon, and such convergence has been persistent."

In a press conference following the decision, ECB President Mario Draghi urged governments to take fiscal measures to supplement the central bank's monetary stimulus and reinvigorate the euro zone economy.

"In view of the weakening economic outlook and the continued prominence of downside risk, governments with fiscal space should act in an effective and timely manner," Draghi said.

"In countries where public debt is high, governments need to pursue prudent policies that will create the conditions for automatic stabilizers to operate freely. All countries should reinforce their efforts to achieve a more growth-friendly composition of public finances," he added.