Angel Gurria, head of the Paris-based Organisation for Economic Cooperation and Development (OECD), encouraged ECB President Mario Draghi to "go as far as he can" but added: "There's only so much central banks can do. Basically all they can do is wait until the governments do the right thing."

With Switzerland refusing to share information based on stolen data, India will provide independent evidence on black money account holders, its alternate but not preferred position, Finance Minister Arun Jaitley has said.

Earlier on Wednesday, International Energy Agency's chief economist Fatih Birol also said that he expects prices - hovering at April 2009 lows - to rebound later this year.