The duo were reported by French sports newspaper L'equipe as having submitted tests showing traces of banned corticosteroids following the final of the French Top 14 rugby competition on June 24.

A third player for the Racing 92 club, Argentinian Juan Imhoff, was also implicated in the "anomalous" results following testing by the French Anti-Doping Agency (AFLD).

All three attended a hearing at the French national team training base in Marcoussis alongside a lawyer.

They all refused to speak to reporters afterwards.

Racing have denied the players breached anti-doping rules or obtained therepeutic use exemptions (TUEs) to take otherwise banned substances.

They claim the case relates to "treatment by an authorised channel", and added they are "on the side of law, ethics and love of a clean sport".

Carter and Rokocoko's manager Simon Porter has also claimed the duo were notified of the results a few weeks ago but had done nothing wrong.

He suggested that Carter had used a corticoid for treatment of a calf injury, while Rokocoko was recovering from a knee injury.

"They were told they had nothing to worry about, that all of the exemptions and declarations were in order so the boys have been pretty relaxed about it," Porter told the New Zealand Herald.

"They're not enjoying the attention that this brings but they're pretty relaxed because they've been given the assurances that they've done nothing wrong."

No results of the hearing were made public, with the anti-doping panel now expected to spend the next three to four days deliberating the cases.

If they are cleared, it remains possible the AFLD could appeal the verdict.

Use of some corticosteroids is fully if injected into a joint; used on the skin, or taken nasally.

But a TUE is required if taken orally, injected into a muscle, or taken by suppositories.

Racing 92 beat rivals Toulon 29-21 in the Top 14 Final at the Nou Camp in Barcelona as World Rugby Player of the Year Carter produced a man of the match performance.