ECB ‘very likely’ to buy sovereign bonds: Ex-Member

The European Central Bank is highly likely to start buying government bonds in the first half of next year, a former member of the Bank's executive board told CNBC on Monday.

"In my view it is very likely that eventually the governing council will agree to buy government bonds. My expectation is, maybe in Spring next year, or at least in the first half of 2015," said Juergen Stark, a German economist who was previously a decision maker at the ECB.

Speculation has been rife as to if and when the Bank will start a U.S -style sovereign bond-buying program to stimulate the euro zone economy and quell deflationary pressures. The ECB has already launched a slew of measures to ease credit conditions in the region, including cutting interest rates to record lows and announcing plans to purchase covered bonds and asset-backed securities (ABS).

Read MoreECB's Draghi: Buying sovereign bonds is an option

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Stark said he doubted whether the covered bond and ABS purchases would boost the ECB's balance sheet by the aimed for 1 trillion euros ($1.2 trillion)—and would therefore push the governing council to approve sovereign bond buying.

Speaking on Monday, ECB President Mario Draghi reiterated that the Bank remained "unanimous in its commitment to using additional unconventional instruments if needed."

He added: "The other unconventional measures might entail the purchase of a variety of assets, one of which is sovereign bonds."