Chegin, linked to more than 30 race-walkers implicated in doping cases, was supposedly tracked down while training top athletes in the remote town of Karakol in Kyrgyzstan.

"The team of the Department of Investigations of Anti-Doping Rules Violations, together with two DCOs (Doping Control Officers), traveled to the city of Karakol in the Issyk-Kul region of the Kyrgyz Republic to conduct information on the possible violation of anti-doping rules by the athlete's staff of the Russian national team in race walking," a RUSADA statement said.

"In the course of the activities carried out, the fact of the direct participation of the lifetime disqualified trainer Chegin V.M. in the conduct of training activities at the stadium of Karakol with the participation of athletes of the Russian national team in race walking. 

"[On] April 25, 2018 in the All-Russian Athletics Federation was sent a demand to provide explanations for this fact in the shortest time. 

"On the same day, RUSADA was notified by the Ministry of Sport of the Russian Federation. 

"An investigation is under way."

German ARD journalist Hajo Seppelt has also tweeted that a source has told him that Chegin was involved in a training camp in Cheboksary, Russia in March this year supposedly attended by athletes including the world 20 kilometres silver medallist Sergej Shirobocov.

Shirobocov has never been implicated in a doping case and it is not clear if this will form part of the RUSADA investigation. 

Chegin turned Russia's race walkers into a world-beating team and was rewarded with near-total control of a state-funded training centre in Saransk named in his honour.

But his success was undermined in recent years by more than 30 failed tests and doping cases by Russian walkers, more than 20 of them from his centre.

In July 2014 the All-Russia Athletics Federation (ARAF) dropped Chegin from their team support staff for that year's European Championships in Zurich after then President Valentin Balakhnichev claimed the high number of positive cases involving his athletes had "tarnished Chegin’s career".

The ARAF, however, did not prevent Chegin from continuing to coach walkers within Russia and he was also spotted on the course during the Championships in the Swiss city, encouraging athletes he worked with. 

He was eventually banned for life by RUSADA in March 2016.

Athletes coached by Chegin implicated in at least one doping case include current or stripped Olympic or world champions Valeriy Borchin, Sergey Bakulin, Olga Kaniskina, Sergey Kirdyapkin, Olimpiada Ivanova and Elena Lashmanova.

Most of these individuals were banned due to biological passport anomalies, suggesting the presence of blood boosting drugs such as erythropoietin.