Thousands of people marched in Moscow under Russian flags, balloons and banners on Thursday to back Vladimir Putin's bid to return to the presidency and counter opposition protests that have challenged his authority.

People wrapped themselves in warm hats, scarves and coats on a chilly national holiday and started marching along the banks of the Moscow River behind a long blue banner declaring: Our vote for Putin.

Organisers said tens of thousands were likely to take part in the march and a rally in a sports stadium which the prime minister was widely expected to address.

The former KGB officer is on course to win the election on March 4, extending his 12-year rule for another six years, although tens of thousands have shown their concern over his return to the Kremlin by protesting in the past two months.

The atmosphere was festive on Defender of the Fatherland Day, a holiday which honours the armed forces.

I support Putin. He's an FSB (security service) guy and my father is too so I like him, said Rostislav Galeyev, 20.

Police were out in force because the opposition communists and nationalists planned rallies in other parts of the capital.

The communists and nationalists also staged small rallies in several other cities across the vast country of more than 140 million people but there were no immediate reports of clashes.

Putin's campaign team, which protrays him as a strong leader and guarantor of stability, has failed to quell reports that many of the people at pro-Putin rallies are paid or coerced into attending by employers and trade unions.

I came here with friends. They said they would pay each of us 2,000 roubles ($67), said a 21-year-old man who gave his name only as Alexander after he and his friends were brought into Moscow by bus from just outside the city.

If I had a choice I would vote for (nationalist Vladimir) Zhirinovsky, but our voices don't count.

Putin says that even if some are obliged to attend, there are many more who want him to return to the post he held for eight years until 2008, a period in which Russians enjoyed an economic boom on the back of a surge in the price of oil, Russia's main export commodity.

PUTIN ON COURSE TO WIN IN FIRST ROUND

The latest opinion poll this week showed he would win more than 50 percent of the votes on March 4, enough to avoid a second-round runoff. His rivals include Zhirinovsky, communist Gennady Zyuganov and businessman Mikhail Prokhorov.

After initially insulting the protesters who have taken part in opposition rallies sparked by allegations of fraud in a parliamentary election won by Putin's party on December 4, the 59-year-old leader has allowed their main rallies to go ahead.

But he has accused foreign governments of backing the opposition protesters and has met none of their main demands, including a rerun of December's election, the release of people the opposition call political prisoners and far-reaching political reforms.

He has announced token electoral reforms but opposition leaders who met President Dmitry Medvedev this week say they do not go far enough and will not be implemented quickly. The next opposition protest in Moscow is planned for Sunday.

Putin was president from 2000 until 2008, when he was barred by the constitution from running for a third successive term, but has remained dominant as prime minister.

If he wins two more terms, he could stay in power until 2024. The opposition protesters say a growing number of Russians feel they have no say in the way Russia is run and that it is bad for any country to be led by one person for so long.

(Writing by Timothy Heritage)