The future of Edinburgh Rugby was plunged further into doubt today when the club submitted their resignation to the Scottish Rugby Union.

The move means Edinburgh are unable to play Magners League or Heineken Cup fixtures, although the season does not start until September.

But Edinburgh owner Bob Carruthers claimed the club had not been a member when he bought them from the SRU a year ago.

The ability of their players to train was also in question as they are no longer part of the SRU's insurance scheme.

The development is the latest low point in the bitter dispute between Carruthers and the union, which may be destined for the courts.

Edinburgh stopped 12 of their players training with their Scotland team-mates last week.

An SRU statement this morning read: "Edinburgh Rugby Limited have confirmed that they wish to resign as an associate member of the SRU.

"Under IRB regulations, as a result of Edinburgh Rugby's withdrawal from membership, no club or team that is a member of any rugby union and in membership of the IRB is now permitted to play against them.

"Furthermore, as the club is no longer an associate member of the SRU, it is not entitled to be a member of the SRU club accident insurance scheme, which is only open to member clubs.

"Therefore, Edinburgh Rugby's contracted players are no longer insured by the governing body's scheme for the purposes of training or playing."

Carruthers appeared to be taken by surprise by the ramifications of the resignation.

He said: "We bought a club and they weren't a member of the SRU. We only joined last September."

In response to the revelation that Edinburgh would not be able to play fixtures, Carruthers said: "They didn't tell us that when they sold us the club so if that's the case then we would have been misled."

An SRU spokesperson responded: "The Edinburgh team technically would have remained as an SRU team last summer under IRB regulations until the paperwork cleared in regard to their application to become an SRU member club in their own right.

"They would be treated as an SRU pro team, pending clearance of their paperwork.

"Edinburgh would have been insured from August 2006 but this always covers pre-season preparation retrospectively, as would be the case with any club going through this process."

Edinburgh bosses were in talks with their lawyers this afternoon and were expected to release a statement later.

The dispute centres on the distribution of Magners League and Heineken Cup fees, with Carruthers claiming the SRU owe them a six-figure sum, which the union deny.

The Edinburgh owner last week claimed SRU chief executive Gordon McKie had threatened to withdraw all funding and stop the club playing fixtures if they issued legal proceedings.

But Carruthers insisted he was preparing for a two-year legal battle if no agreement could be reached, and that litigation could be three weeks away.

The SRU then reported the club to the IRB for failing to release players for international training, but Carruthers said they were not obliged to until July 13th. The Scotland squad were on holiday this week.

The row escalated over the weekend with Carruthers warning his leading players they might have to find new clubs if McKie carried out his alleged threat.

Edinburgh had embarked on an ambitious recruitment drive this summer but star signing Stephen Larkham's agent earlier said he would be seeking urgent talks with club officials.

And reports also claimed Scotland star Chris Paterson had played his last game for Edinburgh under the present ownership.