*PRESIDENT PUTIN SWORN IN*

VLADIMIR PUTIN was sworn in for another six-years as Russian president on Monday, buoyed by popular support but weighed down too by -

A costly confrontation with the West, a fragile economy and uncertainty about what happens when his term ends.

Standing in the ornately-decorated Andreyevsky Hall in the Grand Kremlin Palace, with his hands on a gold-embossed copy of the constitution, Putin swore to serve the Russian people, to safeguard rights and freedoms, and protect Russian sovereignty.

Putin's inauguration for a fourth term as Russian president came two months after more than 70 percent of voters backed him in an election in which he had no serious challengers.

His most dangerous opponent Alexei Navalny, was barred from running and on Saturday Navalny and hundreds of his supporters were detained by police while protesting over Putin's new term under the slogan: Putin is not our tsar.''

In a speech after the swearing in  ceremony, Putin said that in the next six years Russia would prove a strong, muscular player on the world stage, backed by a powerful military, while pushing hard to improve life for its citizens.

''Taking up this post, I feel a colossal sense of responsibility,'' Putin told his audience of Russian officials and foreign dignitaries, among them former German Chancellor Gerhard Schroeder.

''The object of my life and my work will be to serve the people and the fatherland,'' he said.

For the short journey from his office to the inauguration ceremony, Putin traveled in a new Russian-made limousine.

From now the limousine will replace fleet of imported vehicles Putin uses, state television reported. With Putin sworn in, immediate attention will turn to whom Putin will nominate as his prime minister.

If he asks the current holder of post, his loyal lieutenant Dmitry Madvedev to stay on, that will signal continuity.

If he chooses someone new, that could presage a fresh approach on policy and will also trigger speculation that Putin is grooming a successor.

Once his term ends in 2024, the constitution bars him from running again.