GREATER Western Sydney chief executive Dave Matthews says the club has nothing to hide and believes no sanction is necessary for embattled midfielder Lachie Whitfield.

Fairfax Media reports the AFL has finished an investigation into whether the 22-year-old stayed at the home of former Giants welfare manager Craig Lambert in May last year in order to avoid an illicit drug test he allegedly feared he may fail.

The report claims text messages between Whitfield and his ex-girlfriend are central to the investigation.

Whitfield, who re-signed with the Giants for a further two seasons earlier this year, faces the prospect of bans from two to four years if it is proven he deliberately evaded a drug test.

When asked about the controversy on Tuesday, Matthews said the Giants had acted appropriately, and made the AFL aware of the situation as soon the club's board found out about the allegations in July.

Mathews refused to go into any specifics about the investigation, but said the club had referred the matter to its own integrity committee, which then commissioned a report that was handed to League officials. 

"We certainly thought the report that was commissioned independently by us covered all bases," he said.

"The report found that there was no really significant basis to support the allegations that were put forward.

"Our club, in my view, has acted properly every step of the way.

"We received allegations, we took them seriously, we had them investigated, we alerted the AFL immediately, and their process is ongoing.

"In that regard we didn't see any reason to take any action at all.

"We've since extended Lachie Whitfield's contract, he's an important player to our club and we support him.

"The report that we received was vindication for Lachie."

Whitfield has played 19 games this season, and 70 in total, since the Giants selected him with pick No.1 at the 2012 NAB AFL Draft.

Matthews said it was premature to speak about whether the Giants would stand the 21-year-old down if the AFL investigation found evidence of any truth to the allegations.

"They're just hypotheticals, we've still got to see what the AFL investigation concludes," he said.

"The AFL hasn't advised us of any specific conclusions they've reached, so that’s what we've got to wait for."

The AFL released its own statement on Tuesday afternoon, saying: "The AFL wishes to advise the League's Integrity Department has been conducting a detailed investigation into a matter involving a current-listed player of the GWS Giants Football Club, and two members of staff, who have since left the club but remain employed within the industry.

"The AFL was notified by the GWS Giants of an allegation by a member of the public.

"The AFL will now forward its completed brief to the Australian Sports Anti-Doping Authority (ASADA)."

Whitfield, the No.1 pick in the 2012 NAB AFL Draft, is expected to be available for selection in next week's qualifying final against the Sydney Swans. 

ASADA revealed it agreed the AFL would lead the investigation, and now is waiting to be briefed on what the League found. 

"ASADA received information from a member of the public in July 2015 regarding this matter," an ASADA spokesperson said in a statement provided to AFL.com.au on Tuesday afternoon.

"We consulted with the AFL in August last year and both parties agreed that the AFL would be best placed to conduct the investigation into whether there was a breach of the AFL rules and/or of the AFL Anti-Doping Code.

"ASADA has not yet been appraised of the evidence collected by the AFL in their investigation.

"As such, ASADA cannot comment further on this matter."

Giants coach Leon Cameron said Whitfield, who was at the club with his teammates on Tuesday, was in good spirits.

Cameron expected the midfielder to be available when GWS takes on the Sydney Swans in their qualifying final at ANZ Stadium on September 10.

"It's obviously not ideal, but he's all good; he's OK and around his teammates," he said.

"That will sort itself out in time but at this stage he'll be ready to go next Saturday."