Fresh doubt was cast today on the future of Dmitri Medvedev as Russia's President after a report suggested that he could step down next year to pave the way for the return of Vladimir Putin.

The respected business daily Vedomosti said that a proposal to extend the presidential term from four years to six was part of a calculated plan to restore Mr Putin to the Kremlin. Mr Putin is currently Prime Minister.

Mr Medvedev announced the reform today in his first state-of-the-nation address to Russia's legislators. The newspaper quoted an unidentified Kremlin official as saying that the initiative had been drawn up last year, while Mr Putin was still president.

Mr Medvedev, 43, would oversee the constitutional amendment and push through some unpopular social reforms before resigning in 2009 and calling a snap election to make way for his mentor.

Mr Putin, 56, would then govern for two more terms, totalling 12 years. This would take his second presidential era to 2021, the paper noted, one year beyond the completion of the so-called "Putin Plan" for Russia's economic and social development.

Mr Medvedev also called for an extension of the term between elections to the Duma, Russia's lower house of parliament, from four years to five. The report suggested that this was further evidence of Mr Putin's imminent return, because the reform meant that the next time presidential and parliamentary elections coincided would be 2021.

Mr Putin's spokesman said that he saw no grounds for a return to the Kremlin next year "because the term of the existing president will continue in 2009". But the denial will do little to dampen speculation that Mr Medvedev remains a stop-gap leader until Mr Putin decides to reclaim the presidency.

Mr Putin resisted pressure from hard-line factions within the Kremlin last year to change the Constitution so that he could run for a third consecutive term. Under the Constitution, a president is limited to two terms.

Instead, he chose Mr Medvedev as his successor, a man without known ties to either the security services or the Communist Party during the Soviet era. He was presented as a liberalising figure with a modern outlook on the world.

As Prime Minister, however, Mr Putin has taken wide-ranging powers to run the country and has extended his reach into foreign policy, traditionally the reserve of the President. The Kremlin-controlled party, United Russia, also holds two-thirds of seats in the Duma, making it inevitable that the constitutional amendment will pass.

The unnamed Kremlin official told Vedomosti that Mr Putin had resisted changing the Constitution while he was president because it would have looked unethical. His successor's decision to extend the presidential term, however, provided the necessary pretext for a resignation and for Mr Putin's return to power in a way that appeared to be constitutional.

Times Recommends

• New York has lost its edge
• Copenhagen will fail – and quite right too
• More than 17,000 new underwater species found