The World Anti Doping Agency (WADA) has alleged that “abnormally high” amounts of a banned substance has been detected in old urine samples from Essendon players.

WADA claimed two player samples returned high amounts of thymosin beta 4, the substance the club was accused of administering to its players, Fairfax Media reported.

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The two samples were part of a total of 27 taken from Essendon players on the club’s list between December 2011 and August 2012 — the period sport scientist Stephen Dank is thought to have injected players with an as-yet unproven substance.

While thymosin beta 4 occurs naturally in the body, WADA alleged the amounts detected were evidence of external administration. It sent the samples to a German laboratory for further testing.

Essendon chief executive Xavier Campbell said the claims proved “nothing” new.

“Nothing that has come from the [WADA] submission has altered my view or confidence in the players position,” Mr Campbell said in a statement.

“It is clear that WADA does not know what the results mean. There was no supporting documents or evidence.

“There are real doubts as to the significance of the claims.”

Australia’s anti-doping agency ASADA cleared Essendon players of any wrongdoing in March 2015.

The new findings were simply “additional circumstantial evidence” of thymosin beta 4 use, ASADA boss Richard Ings told News Corp.

ASADA reportedly did not test urine samples using the same method as WADA.

WADA’s appeal against the not guilty verdict for Essendon players will reportedly begin in November. It will be able to present new evidence.