The Bath chief executive Bob Calleja launched an inquiry on Sunday following allegations that a number of the squad were involved in a fracas with Harlequins players. Bath, who have made no official comment, hope to complete their investigations within the next few days. But Harrison, 35, has left the club with immediate effect and will return to Australia as soon as possible.

Harrison joined Bath from Ulster on a one-year deal last summer and had only just signed a 12-month contract extension in December. The alleged incident took place in a London pub on May 10, the day after Bath's Guinness Premiership semi-final defeat to Leicester.

Regional Rugby Wales was set up as a governing body to protect the interests of the four Welsh regions with regard to the WRU's activities but persistent issues with the WRU appear to have forced Moffet's hand. The pair blame the Welsh Rugby Union for what they say is a failure to reach a new WRU-regions participation deal.

"Welsh rugby still does not have the certainty of a solution it so desperately needs," said Moffett.

The statement read: "Gallacher... will take over the reins to continue the regions' negotiations with the WRU regarding a revised participation agreement that has so far failed to materialise."

Moffett was WRU boss before leaving that role to be succeeded by current chief Roger Lewis. There has been little progress on a new participation agreement for the regions with the WRU and the dispute has even gone to court.

"We're miles apart and that's the unfortunate thing," ex-Scarlets chief executive Gallacher told BBC Wales. "We are very concerned now. We had hoped that this would have been put to bed, certainly by the start of the Six Nations or indeed by the end.

"And here we are now going into June and still as far apart, probably, as we were three years ago. The stumbling blocks are player release, funding - all the conditions of the Rugby Charter that the WRU wants to put in we're totally against.

"We are independent businesses after all and the control that the WRU is seeking through the agreement is not acceptable to the four regions."

Greening won 24 England caps in a playing career which included the 1999 World Cup and the 2001 Lions tour to Australia. He was forced to retire in October 2005 due to a foot injury sustained in Wasps 2005 Guinness Premiership final victory over Leicester.

"I'm delighted to have the opportunity to work with head coach Danny Wilson as he is a very talented young coach and we share the same desire and mindset. It will be a great learning curve for me to work along side him," said Greening.

Brookes can play either loosehead or tighthead and last month helped Ireland Under-20s defeat France away from home. He's also previously starred for Ireland Under-18s last year as they reached the final of the FIRA European Championships in Italy.

This is the latest blow to coach Robbie Deans' plans after Hugh McMeniman and wing Digby Ioane were recently ruled out with long-term injuries. The squad is due to be announced later this week.