The Finn was a late replacement for the fight after Joshua's scheduled opponent Dillian Whyte failed a drugs test himself the weekend before their planned fight at The O2 on 12 August.

Whyte later said he was "shocked and devastated" to learn of the findings and intended to prove his innocence.

Matchroom Boxing, Joshua's promotional team, has now confirmed that Helenius had "returned an adverse analytical finding" after being voluntarily tested on 11 August.

In a statement, Matchroom Boxing said they were first notified about the adverse finding this Friday, 13 days after the fight.

It read: "Today, the Voluntary Anti-Doping Association (VADA) has informed Matchroom and the British Boxing Board of Control that Robert Helenius has returned an adverse analytical finding as part of a random anti-doping protocol.

"Helenius was voluntarily tested on Friday August 11 before the heavyweight fighter's defeat by Anthony Joshua in London on Saturday August 12. The result was made known to Matchroom today (Friday).

"Matchroom defers to the relevant regulatory authorities on next steps. We vehemently continue to support voluntary anti-doping testing. We are committed to promoting a clean and fair sport for all athletes."

Joshua knocked out Helenius in the seventh round to keep himself on course for a fight against Deontay Wilder.

Helenius has not yet publicly commented on the findings.