An "institutional conspiracy" on an "unprecedented scale" existed in Russia to help some 1000 of its athletes benefit from doping.

A "systematic and centralised cover up" of doping dated back to at least 2011, and was in use at the 2012 London Olympics, according to a report.

More than 30 summer and winter sports, including football, were part of the "refined conspiracy" - which carried on until at least 2015.

Among the implicated athletes were four medallists at Sochi 2014 and five from London 2012.

The findings were made by Dr Richard McLaren, commissioned by the World Anti-Doping Agency, to investigate allegations of widespread doping across Russia.

On Friday, Dr McLaren published the second half of his damning report, the first half of which was published in July.

Announcing his findings in London, Dr McLaren described the conspiracy as evolving over the years from "uncontrolled chaos to an institutionalised and disciplined medal-winning strategy and conspiracy".

It operated "on an unprecedented scale" and existed across summer and winter sports.

"This systematic and centralised cover-up and manipulation of the doping control process evolved and was refined over the course of the use at London 2012... and the winter Games in Sochi 2014", Dr McLaren said.

National team coaches were found to have bought performance-enhancing drugs for their lead athletes, while anti-doping agencies corrupted doping control officers.

The Russian sports ministry the accusations of state doping, and said it would study the report.

The first half of the report had already cited "state-sanctioned" doping by Russian athletes at the 2014 Sochi Games.

Among those findings were that stored samples sent to a London laboratory for tests had been opened.

Other samples based in Moscow were found to have "disappeared", while it was "inconceivable" that Russia's sports minister Vitaly Mutko was unaware of the situation.

In July, McLaren described the doping deception as "beautiful in it's simplicity", but his report was slammed by Russian President Vladimir Putin as political interference.

WADA then recommended Russian athletes be banned from the Rio Olympics - three weeks before they began.

An independent WADA report, published in November 2015, made similar findings about Russian doping.

Subsequently, the International Association of Athletics Federations voted to suspend the Russian athletics federation - a ban which was upheld for the Rio Games.

The International Olympic Committee, however ruled against a blanket ban - instead allowing individual federations to choose whether to permit Russian athletes.

Eventually, Russia took 271 athletes to the Games from an original list of 379.

Russian athletes were then banned entirely from competing at the Paralympic Games.