According to the Financial Times, a close associate of Mr Prodi said that the prime minister’s answer was not final. He has not taken a decision about his future following his impending departure from Italian politics.

The associate was not certain whether Mr Prodi wants to experience the kind of reproach that Gerhard Schroder had faced when he quit as German chancellor in 2005 and accepted from Mr Putin a top post in the Nord Stream Baltic pipeline.

South Stream is a joint project between Russia’s Gazprom and Italy’s Eni. It is expected to pump 30 billion cubic meters of Central Asian gas to Europe annually from 2012, at an estimated cost of $14 billion.