(AFP) - Police have prepared to head to Moscow as part of a widening probe into the death of ex-Russian spy Alexander Litvinenko, as diplomatic strains caused by the affair began to show.
Britain has sought to downplay the impact of the radioactive poisoning scare on its ties with the Kremlin, repeating that it has asked for Russian help and that Moscow has given assurances, reports Trend.
But Russian Foreign Minister Sergei Lavrov was less restrained Monday, saying bluntly that the affair is harming relations between the two countries.
"It's unacceptable that a campaign should be whipped up with the participation of officials. This is of course harming our relations," Lavrov was quoted by Interfax news agency as saying during a visit to Brussels on Monday.
The comments came as officials said nine counter-terrorism officers were expected to leave "very soon" for the Russian capital, where President Vladimir Putin has dismissed the allegations as politically motivated.
According to a report in The Guardian daily, the officers were to interview the three Russian men who met Litvinenko on November 1, the day he fell ill, about three weeks before he eventually died.
The trio -- businessmen Andrei Lugovoi, Dmitri Kovtun and Vyacheslav Sokolenko -- have all protested their innocence, while Lugovoi has said that he believes they are being framed by the real culprit.
But as the investigation continues, the political dimension of the affair is becoming increasingly fraught.
At the weekend officials confirmed that Russian authorities had sent a letter to Foreign Secretary Margaret Beckett raising the issue of a death-bed letter apparently written by Litvinenko accusing President Putin.
In the letter, read out by his spokesman after his death, the former Russian agent pointed the finger directly at Putin, whom he described as "barbaric and ruthless".
There was no immediate response from Britain's Foreign Office Monday to the Russian minister's comments.
Home Secretary John Reid reiterated Sunday that he was confident London was getting the necessary assistance from Moscow over what happened to the former Russian agent.
On Monday Reid, meeting his European Union (EU) counterparts for regular talks in Brussels, confirmed plans for police to head to Russia -- and signalled that they would leave no stone unturned in their investigation.
"I said yesterday that we would widen the circle of our operations, and our information and our investigation," he told reporters.
"The British police will be going to Russia to continue their inquiries," he said, vowing that the investigation "will continue to go whereever the evidence leads."
In another unexpected twist in the story, Litvinenko's father was quoted Monday as saying his son had requested before his death that he be buried according to Muslim tradition,
The former agent and critic of the Kremlin expressed the wish as he lay dying in his father's arms, Valter Litvinenko told the Kommersant daily.
"He said 'I want to be buried according to Islamic tradition'. I said 'Okay son. It will be as you wish. We already have one Muslim in our family.... The important thing is to believe in the Almighty. God is one,'" he said.
At the weekend Mario Scaramella, an Italian contact of Litvinenko who was confirmed last week to have also been contaminated with polonium 210, said he had five times the fatal level of the substance in his body,