Russian Prime Minister Vladimir Putin rejected calls for a rerun of parliamentary elections, but said recent protests over the results are acceptable as long as protesters remain lawful.

"The results of this election undoubtedly reflect the real balance of power in the country," Putin said in an annual televised chat with the nation on Thursday. "It's very good that United Russia has preserved its leading position."

The prime minister — whose party suffered embarrassing setbacks in recent balloting and who himself will be running for president in March — said that the opposition may take its claims of fraud to the courts.

"The fact that people express their opinion … is an absolutely normal thing as long, of course, as everybody acts within the framework of the law," he said.

But he also accused protest organizers of working to destabilize the country on orders from the West.

"That's a well-organized pattern of destabilizing society," Putin said.

Putin's appearance came after weekend nationwide protests against alleged vote fraud in the Dec. 4 parliamentary elections.

The unprecedented wave of protest poses a significant challenge to Putin less than three months before presidential elections in which he seeks to return to the Kremlin.

Putin said he was glad to see public activity, but also urged protesters to abide by the law.

Meanwhile, the Russian billionaire who plans to challenge Putin in Russia's presidential election said Thursday that his first move if elected would  be to pardon jailed tycoon Mikhail Khodorkovsky.

Mikhail Prokhorov said he would also allow free registration of opposition parties and restore popular elections of provincial governors if he wins the presidency.

Putin has marginalized the opposition forces, tightened election rules and abolished direct elections of governors during his 12-year rule.

Prokhorov, estimated to be worth $18 billion, made his fortune in metals, banking and media. He also owns 80 per cent in the New Jersey Nets.

Khodorkovsky, once Russia's richest man, has been in jail in Russia since 2003 on tax evasion and fraud charges seen as a punishment for defying Putin's power.

Speaking at a meeting with supporters who nominated him for the race, Prokhorov hailed last weekend's protest in Moscow against vote fraud, which attracted tens of thousands in the largest show of discontent in 20 years.

"I deeply understand the demands and the strivings of the people who took to the streets," Prokhorov told reporters, adding that he may join a follow-up protest later this month.

With files from The Associated Press