The International Rugby Board ruled that as Jones-Hughes had previously played for the Australian Barbarians he was unable to turn out for Wales despite claiming eligibility through his father, who was born in the Principality.
A statement said: "The Welsh Rugby Union understood that Jones-Hughes was eligible to play for Wales. Acting upon this understanding and after speaking to Jones-Hughes, who expressed his interest in being chosen as a member of the Wales Rugby World Cup squad, he was named by Graham Henry as one of the 30-man line-up. There is a right of appeal and the Welsh Rugby Union and the player's solicitors are now considering taking advantage of such a procedure."
The Australian Rugby Union's managing director, John O'Neill, said: "We said from the outset that Jason has been very poorly advised on this issue. Had he received better advice the matter would not have reached this stage.
"We now hope that Jason will continue his pursuit of a Wallaby Test cap having already represented his country at schoolboy, under-19 and under- 21 levels as well as being a Wallaby tourist to Argentina. We always believed it was a clear-cut issue. We're extremely pleased with the ruling."
The IRB's three-man regulations committee of New Zealand's Rob Fisher, Alan Sharp, of Canada, and the Argentinian Carlos Tozzi had to rule on the status of an Australian Barbarians match against the touring Scotland team at Penrith last June.
Under IRB regulations, once a player plays for a senior team or the next senior team of one union he is unable to represent another country until a residence period has been served. The matter of debate was whether an Australian Barbarians XV counted as the "next" senior status and the IRB ruled that the side has now taken over the role previously taken by Australia A and the Emerging Wallabies.
Wasps have released Nick Greenstock and Andy Gomarsall. The international duo have been shown the door along with the hooker Simon Mitchell, the Canadian full-back Gareth Rees and the French flanker Florent Rossigneux.
Christian Loader has quit Swansea to join Pontypridd. The Welsh international prop, who last played for Wales against New Zealand in 1997, is back to full fitness after a series of injuries. Glasgow Caledonians have completed the signing of Scottish Exiles lock Steve Griffiths from Leeds.Reuse content