Vladimir Putin, the viral video and the accusation of a cross-border hit

The man's voice is deep and distorted for disguise, and, in the grainy video footage, his head is fully covered with a black balaclava. "I am a former employee of one of the Russian special services," begins the six-minute video message. "The Russian Prime Minister Putin plans to kill the Belarusian President Lukashenko."

The video, while probably not genuine, appears to be the latest salvo in an increasingly nasty battle between Moscow and Minsk before presidential elections in Belarus. Belarusian authorities announced on Tuesday that the elections will be held on 19 December, when Alexander Lukashenko will seek a fourth term in office. Mr Lukashenko, who was famously labelled "the last dictator in Europe", has run Belarus since 1994, and tolerates little dissent.

The video, posted on YouTube a few days ago fits into a pattern of insults and insinuations traded between the two countries, once staunch political allies.

The voice in the video claims that the Russians have set up a top-secret working group, tasked with drawing up various ways of "removing" Mr Lukashenko. The tape says options include a road or air accident, a poisoned gift, or a sniper. But the most likely scenario is a major terrorist act during a big event where President Lukashenko is present.

Vladimir Putin's spokesman rubbished the tape as a fake. "I don't think we should pay attention to such nonsense," Dmitry Peskov told the Russian newspaper Kommersant. "This is pre-election schizophrenia."

Most Russian experts agree that the tape is most likely a provocation aimed either at further worsening relations between Moscow and Minsk, or at boosting Mr Lukashenko's popularity at home. Relations between the two countries have deteriorated markedly in the last couple of years over a series of trade disputes and derogatory comments from President Lukashenko about the Russian leadership.

The latest spat started with a series of programmes on Russian television in recent months that aired allegations of corruption and misdeeds against Mr Lukashenko. All of the rumours were well known to the Belarusian opposition and observers of the country, but this was the first time they had ever been aired on Russian television, which is also available in Belarus.

Russian media have also covered at length the suspicious death of an opposition journalist earlier this month. Oleg Bebenin set up one of the country's leading opposition websites, and planned to run the presidential campaign of Andrei Sannikov, an opposition candidate who intends to stand against Mr Lukashenko in the upcoming elections. He was found dead at his country house – the authorities say he hanged himself, but friends and colleagues claim he showed no suicidal tendencies and had made plans to go to the cinema with friends on the day of his death.

Observers say that, for the first time, Mr Lukashenko is in the unenviable position of dealing with criticism from two fronts – he has no real allies in the West, and now is also facing an information war from the Russians. However, his complete control over political life and the media in the country over the past decade means that no opposition politicians have any broad support among the electorate, and analysts question whether even the ruthless pressure that Moscow is applying will be enough to dislodge him.

The most explicit part of the informal Russian campaign against the moustachioed Belarusian leader is still to come, however. Alexander Valov, a controversial Russian film director, is preparing to release an erotic film about the sexual exploits of a man called Luka, who bears a striking resemblance to the Belarusian President. Mr Valov is known for his notorious 2006 film Yulia which featured pornographic scenes between lookalikes of the Georgian President Mikheil Saakashvili and the Ukrainian politician Yulia Tymoshenko, both of whom were out of favour with the Kremlin at the time.

Mr Valov's film about Mr Lukashenko promises to be no less scandalous than Yulia, which featured a three-way sex scene in a sauna between the two lookalikes and a midget. In one clip already released, the Lukashenko-lookalike discusses the quality of tomatoes with a peasant woman harvesting vegetables in a field, before having sex with her. It is expected that the film will be released later this year, before the elections.