Troshkin claimed his third consecutive victory at the annual event on the largest of the Channel Islands, clocking a time of 2 hours 18.28min to finish ahead of the United States’ Christopher Zablocki. 

Russian athletes are barred from competing in international events, however, as a result of a ban issued by the International Association Athletics Federations (IAAF) in November following allegations of state-sponsored doping.

"It’s clear that it’s an international event and he was not allowed to participate," the IAAF told Athletics Weekly.

"He is ineligible because he is on the banned list.

"The IAAF has commenced an investigation into an alleged breach of IAAF rules."

Troshkin, whose personal best of 2:16:40 was set in French city La Rochelle in 2013, will have his result annulled and he must return the £2,500 ($3,000/€2,800) prize money he won.

"We are aware of the speculation surrounding the Jersey Marathon 2016 male winner Aleksey Troshkin and are currently awaiting for an official ruling from the IAAF as they consider his case," race organisers 3D Events said in a statement.

"We are working with UK Athletics and the IAAF and will provide an updated statement once we have further information."

Earlier this week, Russian Olympic Committee (ROC) President Alexander Zhukov revealed plans to step down from his role to concentrate on his work in the country's Parliament.

Zhukov was appointed amid the Russian doping scandal which saw the nation's track and field athletes banned from international competition.

The country's entire participation at Rio 2016 was then restricted as several International Federations opted to exclude athletes from Russia from the event following the publication of the damning McLaren Report.