The combined wealth of Russian President Vladimir Putin's inner circle stands at nearly $24bn (£18bn) a new investigation has claimed.

In 2016, Mr Putin's official income was was reported at just $133,000 and he has repeatedly denied he is one of the world’s wealthiest men.

But a joint investigation by Russian newspaper Novaya Gazeta and Organized Crime and Corruption Reporting Project (OCCRP), has valued him at considerably more, although it suggested that his wealth may be tied up in a series of “proxies”.

Some of the President’s inner ring have “no obvious explanation for their hidden wealth”, according to the report.

“These proxies’ wealth may be accounted for by the simplest explanation: It may really be Putin’s money. But in Russia, nothing is simple,” the authors wrote.

One alleged “proxy” is Mikhail Shelomov, a relative of Mr Putin, who works at a Russian shipping company for a job which would usually pay around $8,500 a year.

Mr Shelomov is a major investor in a new race track near StPetersburg, and has a personal wealth of $573m according to OCCRP, as well as links to the state energy giant Gazprom.

A childhood friend of the President, Pyotr Kolbin, a former butcher, has amassed a personal fortune of $550m - despite telling the Russian press he is “not a businessman”.

William Browder, a US-born anti-Putin campaigner, told OCCRP Mr Shelomov, Mr Kolbin and other cronies were “nominees” who formally own assets, while really holding them in trust for Putin. While Mr Kolbin has been sanctioned by the United States, Mr Shelomov, who keeps such a low profile the OCRUP could not find any photograph of him, has so far escaped the penalties.