Greece could raise as much as 300 billion euros ($429 billion) if it steps up its efforts to sell off state-owned assets, European Central Bank Board member Juergen Stark was quoted as saying on Saturday.

The ailing euro zone state, whose debt burden stands at around 330 billion euros, currently aims to raise 50 billion euros from privatizations by 2015 to help stave off a fiscal meltdown.

Stark also told the Welt am Sonntag newspaper in an interview that Greece's debt should not be restructured.

The Greek government has shares in listed companies, it owns real estate. Experts estimate the sales potential at up to 300 billion euros, Stark told the newspaper according to a prerelease from its Sunday edition.

A part of these assets must be mobilized to lower the debt level. Furthermore, privatizations cause more efficiency in the entire economy, he was quoted as saying.

Athens is setting up a sovereign wealth fund to pool real estate assets and state stakes in companies such as telecom company OTE, Post Savings Bank and ports.

(Greece) needs to intensify its efforts, Stark also said. (The privatization program) is meant to raise 50 billion euros by 2015 and one should be more ambitious here.

Top EU officials have asked Greece to step up privatizations urgently and suggested setting up a trustee institution to help the process, a call echoed by Stark on Saturday -- similar to the body that privatized East German firms after the fall of communism.

Stark also reiterated restructuring Greece's debt would not help the country emerge from its debt crisis.

If you start (restructuring) softly, for instance by extending the maturities of bonds, that changes little about the level of debt. At the same time efforts to adjust will weaken, Stark told the newspaper.

A hard debt (restructuring) would collapse the banking system -- and the economy too.

(Reporting by Annika Breidthardt; Editing by John Stonestreet)