Russian prime minister Vladimir Putin has warned against the dangers of foreign influence at a campaign rally attended by tens of thousands of people.

With little real competition, Mr Putin is almost certain to win a third term as president in the March 4 election.

During 12 years in power, he has sidelined his political opponents and portrayed himself as the defender of a strong and prosperous Russia. His approval ratings are still running at well above 50% despite the largest opposition protests the country has seen since the 1991 Soviet collapse.

Mr Putin has tried to discredit the protesters by accusing their leaders of being paid agents of the United States working to weaken Russia. His latest references were slightly more subtle as he called on all Russians who "cherish, care about and believe in" their motherland to unite.

"We ask everyone not to look abroad, not to run to the other side and not to deceive your motherland, but to join us," he said from a makeshift stage in a football stadium as a light snow fell on his head.

But he also warned the West: "We won't allow anyone to meddle in our affairs or impose their will upon us, because we have a will of our own."

The pro-Putin rally was held on Defenders of the Fatherland day, a national holiday that replaced the Soviet-era Red Army Day.

As participants marched in columns towards the stadium along the Moscow River, they carried Russian flags and wore armbands in the national colours. Patriotic songs from decades past blared from vans parked along the route. They carried signs saying "As long as we have Putin we have a strong country".

The rally was a response to the opposition protests, which began in December after a parliamentary election that Mr Putin's party won through what appeared to be widespread fraud.

But while the protests have been embraced by Russia's middle class and young urban professionals, many of those who attended the rally showed little enthusiasm. They included workers paid by or dependent on the state, including teachers, municipal workers and employees of state companies. Some said they had been promised two days off in return for attending.