MOSCOW — Russian Prime Minister Vladimir Putin defended Monday his controversial plan to seek a third mandate as president, saying Russia needed stability and was still at risk of a Soviet-style collapse.

Speaking in televised remarks in a rare acknowledgement of public discontent, Putin said his political opponents claimed that "everything is so bad, that it could not get worse".

"Saying that things cannot get worse, I would be careful. It's enough to take two or three wrong steps and everything that was before could overwhelm us so quickly that we would not even have time to look around."

"Everything here is tacked together, both in politics and in the economy," Putin said in a startling admission of the fragility of the stability that he prides himself on bringing to Russia since coming to power in 1999.

"We let the (Soviet) state collapse" in 1991, he said in a punchy, populist interview on prime-time television. "Things got as far as -- we have to say it directly -- civil war."

"The entire Caucasus was drenched in blood," he said, noting the continuing unrest in the troubled North Caucasus and countrywide problems "with crime and terrorism".

"I never sought out this post," Putin added, referring to the Kremlin job, after announcing last month his plan to seek a third mandate as president.

"But if I set out to tackle something, I try to bring the matter to its logical conclusion or, at the very least, to bring this matter to the maximum effect."

He stressed that he had not "clung onto" his presidential position, but referred to one of his political heroes, US president Franklin D. Roosevelt, stressing that he stood for office four times.

If elected president, Putin could serve two more terms lasting until 2024, when he would be 72, making him Russia's longest serving leader since Josef Stalin.

A popular Internet joke shows him morphing into long-serving Soviet leader Leonid Brezhnev, ridiculed in his final years for his slurred speech and passion for awarding himself medals.

In unusually harsh criticism of the Soviet era, Putin argued that the post World War II leaders were less hardworking than him or his protege, Dmitry Medvedev.

"They say that the Brezhnev times will return, the stagnation," Putin said. "But I somehow can't remember that ... the postwar Soviet leaders worked as intensively as do I or the current president Dmitry Medvedev."

The sports-mad strongman, who has flexed his muscles in topless shots, said the Soviet leaders were ineffective "due to their physical condition and due to their lack of understanding of what to do."

Putin remains Russia's most popular politician and analysts say his victory in March elections is all but assured. Medvedev has agreed to become his prime minister in a new government.

"Four years ago, we agreed that such a turn of events was absolutely possible," Putin said of the job-swap, saying it was "decided between us."

Putin spoke after many analysts in the West warned that his planned Kremlin comeback could deal a blow to the US-Russian "reset" in ties and usher in frostier relations with the West.

Speaking on Moscow's ties with the West, the 59-year-old prime minister said Russia would pursue a balanced foreign policy.

"We want to have good neighbourly, friendly ties with all our partners," Putin said. "We are not interested in confrontation."

Nevertheless, he insisted that Russia must develop without "advice and commands from abroad," slamming unnamed Eastern European states that "cannot appoint even a defence minister.. without consulting an ambassador of a foreign state."

He made light of Western attempts to brand him a "hawk", referred to by an interviewer.

"First off, a hawk is a good little bird. I am a person anyway," he said. "I am against any cliches."

Many critics, especially abroad, have accused the former KGB officer of seeking to bully smaller neighbours and pressure them into closer cooperation with Moscow.

"I can tell these critics -- and they are clearly unscrupulous critics: you know what, mind your own business," Putin said.

"Fight growing inflation, a growing state debt, obesity, finally," Putin said in an obvious dig at the United States, where around 25 percent of people are obese, according to a recent Gallup poll.