Sounding as if he was quoting from a dusty KGB manual or a bad movie script, Vladi­mir Putin warned Wednesday that his opponents are prepared to murder one of their own so they can blame it on him.

The Russian prime minister also assured a meeting of his supporters here that if he is elected president Sunday, all Russians can expect nothing but happiness — higher pensions, a firm retirement age (60 for men, 55 for women) and unfettered media besides. Plus state-run television will get rid of commercials.

Skepticism was the dominant reaction on the Internet, where much of Putin’s opposition resides — regular people who since December have been demonstrating for fair elections and honest government.

“What’s next?” was the common refrain.

“They are looking for a so-called sacrificial victim among some prominent figures,” Putin, a former KGB agent, told a gathering of the All-Russia Popular Front, a group organized to support him. “They will knock him off, I beg your pardon, and then blame the authorities for that.”

Boris Nemtsov, a foe Putin appears to despise more than most, tossed the imputation right back. It was up to the authorities, he said, to prevent such an unspeakable act.

“If the head of the federal government, who controls all intelligence agencies, makes a public statement that he has information about such a provocation and such a crime, he must do everything to prevent it and not just publicly scare Russians,” he told the Interfax news agency.

Here in Russia, some sycophants see in even off-hand Putin comments ways to please him.

Nemtsov, a liberal leader from the early post-Soviet days, said that he was taking Putin’s comments seriously and that the opposition should, as well.

“If the authorities fail to do everything to prevent such a scenario,” Nemtsov said, “they will become accomplices in this grave crime being plotted.”

Earlier Wednesday, the Kommersant newspaper reported that the man charged with arranging the murder of investigative journalist Anna Politkovskaya had accused Boris Berezovsky, another Putin bete noir who is living in exile in London, of planning that killing, along with a former Chechen leader, Akhmed Zakayev.

“I can’t comment on this nonsense,” Berezovsky, a 1990s-era oligarch who ran afoul of Putin, told reporters. “It’s too much.”

Putin made no secret of his scorn for Politkovskaya, who wrote critical articles about the war in Chechnya. She was killed on Putin’s birthday in 2006.

An attorney for Dmitry Pavlyuchenkov, the former police colonel accused of arranging her death, told Interfax that his client had implicated Berezovsky as part of a pre-trial deal with investigators.

Putin’s talk of cataclysm has grown ever more menacing as the election approaches, sprinkled with voter-pleasing initiatives. On Monday, Russia’s main television channel reported an elaborate plot to assassinate Putin right after the election. On Tuesday, a widely unpopular governor in the Far East was fired.

On Wednesday, Putin also accused the opposition of preparing to stuff ballot boxes in Sunday’s election so they could blame that on him, as well.

“We know that some are preparing to use techniques to confirm election fraud,” he said. “They’ll throw in ballots and then make accusations, all by themselves. We see it and know this already.”

The rhetoric seemed to hang darkly above Moscow, and it was difficult to know whether it was puffs of smoke or sinister trial balloons.