London's Metropolitan Police have launched a murder investigation into the death of Russian oligarch Nikolai Glushkov.

The 68-year-old was found dead at his London home on Monday. A post-mortem examination found he died from "compression to the neck."

The Glushkov investigation is being conducted by the Counter Terrorism Command, "because of the associations he is believed to have had," according to a Met Police statement.

Nikolai Glushkov — who was granted political asylum in the UK in 2010 — was a former friend and business associate of the late Russian tycoon and Kremlin critic, Boris Berezovsky, whose body was found by an employee in the locked bathroom of his luxury London home in 2013. After Berezovsky's death, an inquest failed to determine whether his death had been caused by suicide or foul play.

Berezovsky, among the oligarchs who built economic empires shortly after the collapse of the Soviet Union, was once a key Kremlin ally. Berezovsky fell out with Vladimir Putin during his first stint as president.

The British investigation into Glushkov's murder was launched after Russia's Investigative Committee announced its own probe into his death.

Read more: Police investigate Russian critic's 'unexplained' death 

Last year, Glushkov appeared on a list published by the Russian Embassy in London of Russian citizens wanted for serious crimes whom the UK had refused to extradite. According to the list, Russia had sought his extradition in 2015 "for committing a number of severe financial offences in the territory of Russia," but the British government refused.

Investigators say there is no evidence to suggest Glushkov's death is linked to the attempted murders of former Russian spy Sergei Skripal and his daughter who were left critically ill after nerve agent poisoning a week earlier in the UK city of Salisbury.

Read more: Novichok nerve agents — Russia's dangerous 'new' poison

'Failure' of UK's obligations under Vienna convention

Russia's ambassador to the UK, Alexander Yakovenko, told journalists on Friday that the Russian Embassy had yet to receive an official response to its inquiry about the investigation into Glushkov's murder.

"The embassy has no information about the launch of the probe into Glushkov’s murder," said Yakovenko, according to Russia's TASS news agency.

"The British side is not responding to the embassy’s inquiry. It is unacceptable and we consider this situation as a failure of the UK’s international liabilities under the Vienna convention of consular access," he said, adding that a relevant inquiry had been sent to the British authorities immediately after the news about the businessman's death at the beginning of the week."

kw, kms (AP, dpa, Reuters)