Russian officials have for the first time admitted the existence of a doping operation which affected some of the world's major competitions.

A report on 9 December claimed more than 1,000 Russians benefited from a doping cover-up between 2011 and 2015.

In interviews with the New York Times, officials acknowledged the programme but denied it was state-sponsored.

"It was an institutional conspiracy," said Anna Antseliovich, acting director general of Russia's anti-doping agency.

Vitaly Smirnov, the 81-year-old who has been a leading sports official since the Soviet era and who has been appointed by Russian President Vladimir Putin to reform the anti-doping system, told the New York Times: "I don't want to speak for the people responsible.

"From my point of view, as a former minister of sport, president of Olympic committee - we made a lot of mistakes."

Smirnov also suggested the leaks made by the Fancy Bears - a group of hackers who have released the medical records of several athletes from around the world - showed Russia had not been competing on a level playing field.

Corruption on an 'unprecedented scale'

In July, an investigation commissioned by the World Anti-Doping Agency (Wada) said Russia's sports ministry "directed, controlled and oversaw" manipulation of urine samples provided by its athletes.

A second Wada report from Canadian law professor and sports lawyer Dr Richard McLaren said the London 2012 Olympics was "corrupted on an unprecedented scale".

According to McLaren's report, salt and coffee were used to manipulate Russian samples and the system was refined over the course of the London 2012 Olympics, 2013 Worlds in Moscow and the 2014 Winter Olympics in Sochi to protect likely Russian medal winners.

Russia won 72 medals at the London Games, 21 of which were gold, and 33 medals at Sochi, 13 of which were gold.

Russian sports officials had previously denied the existence of any doping operation, even as the International Olympic Committee opened disciplinary proceedings against several Russian athletes, while the country also lost the hosting rights to a number of international events.

Russia's athletics team is banned from competition by the International Association of Athletics Federation.