A secretive former Russian spy and oil magnate who was close to Vladimir Putin’s foreign intelligence chief has died in mysterious circumstances near Moscow, reports say.

Well-connected Viatcheslav Rovneiko, 59, was “found unconscious” late at night at his home in an elite gated village.

Doctors could not save him, according to local reports, and the circumstances of his death were unclear although an investigation is underway.

“No signs of a violent death were found on his body,” the reports said.

Rovneiko is believed to have been a Cold War era KGB spy who worked in Belgium with Sergei Naryshkin, now head of the SVR, Russia’s foreign intelligence agency.

He is also reported to have been close to billionaire Gennady Timchenko, seen as one of Putin’s most loyal oligarchs.

Rovneiko’s former business partner was Leonid Dyachenko, whose then wife Tatiana was the powerful daughter of Boris Yeltsin, Russia’s first president.

The pair founded Urals Energy, one of several major oil players he was involved with.

The company was floated in London in 2005.

He had business interests linked to the UK, Belgium, Luxembourg and Cyprus, according to reports.

He was reported in 2006 to have held a Belgian passport.

Rovneiko was a graduate of Moscow’s prestigious Institute of International Relations (MGIMO), a training school for spies and diplomats.

Russian business databases showed the ex-spy as a man with no face, and he was known as highly secretive.

He was married to fellow MGIMO student Irina, 63.

Their son Nikolay, 40, worked as an investment banker in London, and studied at Kingston University in the south west of the city.

- Will Stewart, Ap with news.com.au