The Australian Rugby Union wants sanctions imposed on any overseas clubs found pressuring players to withdraw from the sport's showcase, the Rugby World Cup.

Several professional players from smaller, less wealthy rugby nations including Samoa, Tonga and Fiji have withdrawn from the World Cup, preferring to remain with British clubs.

ARU chief executive John O'Neill had noted concerns that some players may have been coerced into withdrawing under the threat of losing lucrative club contracts.

"It's very puzzling and we find it inexplicable that they would choose to play club rugby instead of for their national team," O'Neill said in Adelaide.

"If it's a blatant disregard and blatant abuse of the (International Rugby Board) regulations ... then it is a disgrace.

"At this stage, I haven't seen absolutely unambiguous evidence but I have heard what some of the national coaches of some of these smaller unions have said and if it's true, it's pretty alarming."

O'Neill called for nations affected to hand any evidence of coercion to the IRB and urged the IRB to investigate.

But he admitted getting proof could be difficult and that some players may simply have chosen club payments over unpaid national service.

"A lot of people were talking off the record and a number of the national coaches of some of these smaller unions are speaking quite liberally off the record about what they believe is happening," said O'Neill.

"It's time to put up or shut up - produce the evidence and allow the IRB to take some remedial action."

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