Dmitry Medvedev was sworn in as president in a solemn ceremony in the Kremlin's throne room on Wednesday, ushering in an unprecedented period of dual rule with his predecessor Vladimir Putin, who becomes prime minister.

Medvedev, a 42-year-old former corporate lawyer and longtime Putin ally, placed his hand on a red, leather-bound copy of the Russian constitution to take the oath of office before 2,000 invited guests.

Minutes earlier, Putin had entered the Kremlin alone and thanked the Russian people for their trust and support, encouraging them to support Medvedev and wishing him well.

Putin named Medvedev as his preferred successor last December, ensuring his victory in the March polls.

But the Kremlin leader will retain major political influence after quitting, both in his role as prime minister and as head of the ruling United Russia party which controls parliament.

The inauguration ceremony in the Grand Kremlin Palace broadly followed the pattern set in 2000, when Putin was sworn in, allowing officials to stress continuity and the smooth transition of power.

Access was not granted to foreign media.

The constitution, adopted under Yeltsin, gives the president strong powers, including the right to define Russia's foreign and domestic policy, appoint key ministers and control key security and defence agencies.

Putin, in his time in office, further boosted Kremlin power by assuming the right to name hitherto elected regional leaders and taking control of parliament.

Putin has said he sees no problem working with Medvedev with whom he shares common views on Russia's future. But Russia's history, dominated by single powerful rulers such as Josef Stalin and the Tsars, knows few examples of smooth co-existence.

Short-lived rivalries between Yeltsin and his powerful prime ministers usually ended in the resignations of the latter.

Putin has preferred technical, and weak, premiers. But when he is confirmed as a new prime minister by parliament on Thursday and lands in his new riverside office in central Moscow, the picture is sure to change dramatically.

Putin, who has presided over eight years of uninterrupted economic growth, has said he will focus on making Russia one of the top seven global economies by 2020. He has promised not to seek any extra powers in his new job.

Eight years ago, the departing Yeltsin left Putin a pen with which he used to sign laws as a symbol of a handover of power. Putin said in a newspaper interview last month, he would take the historic pen with him rather than leave it to Medvedev. - Reuters