A Ukranian-born millionaire businessman with links to Donald Trump has reportedly died in unexplained circumstances.

Alex Oronov, a 69-year-old naturalised American citizen who ran an agricultural business in his native Ukraine, died on 2 March, according to a Facebook post by Ukranian politician Andrii Artemenko.

Mr Oronov is reported to have set up a secret meeting between Donald Trump’s personal lawyer Michael Cohen – to whom he had family ties - and Russian officials where a “peace plan” is said to have been hatched to give Russian President Vladimir Putin control of the Crimea.

Mr Cohen is understood to have an extensive network of personal and business relationships in the Ukranian-American community – and his associates included Mr Oronov, a partner in the ethanol business the lawyer’s brother, Bryan, set up in Ukraine.

The “peace plan” meeting brought together Mr Artemenko, Mr Cohen and Felix Sater, an American-Russian long-time business associate of Mr Trump who is reported to have ties to the Russian mafia.

Details of this meeting are believed to have ended up on the desk of Michael Flynn, Mr Trump’s former security adviser who was forced to resign last month over his alleged secret dealings with Russian officials.

The New York Times – which Mr Trump has repeatedly accused of producing “fake news” - reported the meeting between Mr Artemenko, Mr Cohen and Mr Slater.

In his lengthy Facebook post, Mr Artemenko describes himself as a pawn in a diplomatic game and said the stress created by the article and the negative attention that followed the article was too much for Mr Oronov.

The post, written in Russian, translates loosely: “Yes, I’m guilty... Alex Oronov, my partner, my friend, my mentor, Alex was a family member of Michael Cohen. And he organised all kinds of stuff, including an introduction and a meeting for me with Michael Cohen.”

It adds: “Unfortunately, his heart could not endure it. He died... Friend, your death will not have been in vain, nor will the deaths of tens of thousands of Ukranians and Russians, Alex Oronov, during this wild, undeclared war! Rest in peace and forgive me if you can, as difficult as that may be!”

The Ukrainian MP points the finger of blame at “overexertion, the nerves, from injustice, from suspicion, from sorrow of misunderstanding”.

The remembrance website legacy.com has a listing for Alex Oronov of New York, with dates that match those of the businessman.

One friend and business associate has so far left a tribute on the site, which reads: “Alex had a huge heart and he did a lot for those who were part of his family and part of his company.”

Conspiracy theorists have pointed to a number of recent deaths of Russian diplomats in the past four months.

Russia’s permanent ambassador to the UN, Vitaly Churkin, died last month in New York after suddenly becoming ill on his way to work the day before his 65th birthday.

It was initially reported he had suffered a heart attack but an autopsy proved inconclusive.

The Russian Consul in Athens, Andrei Malanin, 55, was found dead on the floor of his apartment in Greece in January. Greek police said there was no evidence of a break-in and he was believed to have died of natural causes.

Russia’s Ambassador to India, Alexander Kadakin, 67, was reported to have died of heart failure in January after a “brief illness” according to Indian media.

Russian diplomat Sergei Krivov, 63, was found unconscious having suffered severe head injuries at the Russian consulate in New York on US election day.

According to BuzzFeed, Mr Krivov was initially said to have fallen to his death following a suspected heart attack, but a subsequent report from medical examiners was inconclusive.

Mr Krivov is believed to have been responsible for the security of the consul from American intelligence, although he was initially said to have been “a security guard”.

The Russian ambassador to Turkey, Andrei Karlov, was assassinated in Ankara by a policeman at a photography exhibition on 19 December and another diplomat, Peter Polshikov, was shot dead in his Moscow apartment on the same day.

Former KGB chief Oleg Erovinkin, who was suspected of helping British spy Christopher Steele draft a dossier on Donald Trump, was found dead in the back of his car last Boxing Day.

Mr Erovinkin was also an aide to former deputy prime minister Igor Sechin, who now heads up state-owned oil company Rosneft and is said to have been named in the dossier.