Vladimir Putin has a vast personal fortune and may be one of the richest men in the world, according to a number of former Kremlin insiders.
From their exiles around the world, they spoke to the BBC for a Panorama investigation into the alleged corruption of the most powerful man in the world. Here's what we learned.
He 'has a $1bn palace'
Sergei Kolesnikov told the programme he worked for the Kremlin to collect money from the super-rich, which they believed was to be spent on healthcare, but which was ultimately used “to help build a $1 billion palace for Mr Putin on the Black Sea coast”.
The BBC said it had seen documents from one of the offshore companies that diverted millions of dollars to the palace, which was constructed during Mr Putin’s first term as president.
It said that, according to Mr Kolesnikov, the owner of the company, Lirus Investment Holding, was Mr Putin himself.
Mr Kolesnikov was also allegedly filmed discussing Mr Putin’s secret fortune – investments of up to $440 million – with another Kremlin insider.
Sergei Pugachev, an exiled oligarch who says he helped Mr Putin become president, told the BBC he was “preoccupied with wealth from the start”. He said he visited one of the presidential palaces with Mr Putin during his first term. “We talked about it, he didn’t hide it, he knew he wanted to leave office a wealthy man,” he said.
A vast fortune
Putin's public financial disclosures depict a man of modest means, as far as world leaders go. In April, Putin declared 2014 income of 7.65 million roubles ($119,000). He listed the ownership of two modest apartments and a share in a car parking garage.
Adam Szubin, acting Treasury secretary for terrorism and financial crimes, said in an interview with BBC Panorama that the Russian president has been amassing secret wealth.
He declined to comment on a 2007 CIA report estimating Putin's wealth at $40 billion, but he said the Russian leader's stated wealth is an underestimation.
In pictures: The adventures of Russian President Vladimir Putin
In pictures: The adventures of Russian President Vladimir Putin
Russian Prime Minister Vladimir Putin feeds a horse during his vacation in the Republic of Tyva, Russia, in Augsut 2009
Russian President Vladimir Putin (right) climbs into the under water vehicle 'Sea Explorer-5' during its diving to the Russian sailing frigate 'Eagle' which sank in 1869, near the Gogland island in the Baltic Sea off coast the St. Petersburg region, Russia in July 2013
Russia's President Vladimir Putin is seen through the glass of the C-Explorer 5 submersible after a dive to see the remains of the naval frigate "Oleg", which sank in the 19th century, in the Gulf of Finland in the Baltic Sea on July 2013
Vladimir Putin carries a hunting rifle during his trip in Ubsunur Hollow in the Siberian Tyva region (also referred to as Tuva), on the border with Mongolia, Russia
Russian Prime Minister Vladimir Putin plays the piano during a charity concert in Saint Petersburg on December 2010
Russian President Vladimir Putin throws a Japanese judo expert during a judo exercise at Kodokan September 5, 2000
Russian Prime Minister Vladimir Putin (right) and scientists examining a polar bear on the island Alexandra Land, part of the Franz Josef Land archipalego in the Arctic Ocean
Vladimir Putin receives instructions from a Renault Formula One team member before driving a F1 race car on a special track in Leningrad region outside St. Petersburg on November 2010
Vladimir Putin (left) assisted by Vyacheslav Razhanov fixes a GPS-Argos satellite transmitter onto a tiger during his visit to the Ussuriysky forest reserve of the Russian Academy of Sciences in the Far East in August 2008
Russian Prime Minister Vladimir Putin holds a judo training session at the Top Athletic School during his working visit to St Petersburg on December 18, 2009
"He supposedly draws a state salary of something like $110,000 a year," Szubin said. "That is not an accurate statement of the man's wealth, and he has longtime training and practices in terms of how to mask his actual wealth."
Russian political analyst Stanislav Belkovsky told the BBC he had information from “confidential sources” to also put Mr Putin’s wealth at “$40bn in assets”. He said: “I’m still sure Putin is the richest man in Europe, one of the richest men in the world.”
Huge oil business stakes
The US Treasury told the BBC it has evidence to tie Putin to profits from a businessman on the US sanctions list, Gennady Timchenko, a long-time Putin acquaintance and then co-owner of Gunvor, which trades nearly 3 per cent of the world's oil.
The US government imposed sanctions against a number of Kremlin insiders in 2014 and stated that Vladimir Putin had secret investments in the energy sector. However, the Americans did not directly accuse him of corruption at the time.
"Timchenko activities in the energy sector have been directly linked to Putin. Putin has investments in Gunvor and may have access to Gunvor funds," the department said in a statement announcing the sanctions.
Max Freidzon, another exiled businessman, told the BBC Mr Putin gave him the monopoly to provide oil to an airport in the nineties – in exchange for a secret, 4 per cent stake in his business.
And a yacht from Roman Abramovich
Dmitry Skarga, who used to run the state shipping company Sovcomflot, says he oversaw the transfer of a $35m yacht to Mr Putin. Mr Skarga says the 57m-long Olympia was a gift from Britain's most famous Russian - the Chelsea football club owner Roman Abramovich.
"It's a fact that Mr Abramovich, through his employee, transferred a yacht to Mr Putin," he said. "I was on board of this yacht at the end of March 2002, in Amsterdam. And there was a representative of Mr Abramovich… He said that Roman is the owner of this yacht."
Mr Skarga says the Olympia was transferred to Mr Putin via an offshore company, and that he later managed the yacht for Mr Putin and prepared secret reports on the boat's running costs.
Panorama said Mr Abramovich's lawyers dismissed claims about him as "speculation and rumour".
He ‘is corrupt’
Mr Szubin said: "We've seen him enriching his friends, his close allies and marginalizing those who he doesn't view as friends using state assets. Whether that's Russia's energy wealth, whether it's other state contracts, he directs those to whom he believes will serve him and excludes those who don't. To me, that is a picture of corruption," Szubin was quoted as saying.
The Kremlin has denied such allegations. For his part, Putin has repeatedly said that he has read press reports about his immense wealth, including that he was even the world's richest man, but he has denied those reports as nonsense. In a statement in 2010, Mr Putin's spokesman Dmitry Peskov said Mr Putin "has never had any relationship to" the $1 billion palace.
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