The British Olympic Association has been told its life ban for drugs cheats violates the global anti-doping code.
The World Anti-Doping Agency (Wada) board declared the policy "non-compliant" at a meeting on Sunday.
The BOA intends to take the matter to the Court of Arbitration for Sport (Cas) in a bid to keep the ban.
The decision by Wada's foundation board was widely expected. It follows a week of increasingly heated exchanges between the two organisations. The BOA believes the by-law is an eligibility rule, and that it has the right to decide who can pull on the GB vest at the games. Wada says the BOA rule amounts to an additional sanction. If the BOA loses its challenge to the doping agency's decision, it will have to rethink the by-law which has overwhelming support among British athletes, and previously excluded the likes of Dwain Chambers from taking part in the London games.
"We will vigorously defend any challenge to the policy which bans drug cheats from representing Team GB," the association said.
The BOA by-law imposes a lifetime Olympic ban on any British athlete banned for more than six months for a doping offence.
In October, Cas ruled that the International Olympic Committee's (IOC) own doping rule - which barred offenders who had received bans of longer than six months from competing in the next Olympic Games - was unenforceable.
That allowed Olympic 400m champion LaShawn Merritt to
overturn a ban
that prevented him from competing at the 2012 Games, enabling him to defend his title in London next year.
Following that decision, Wada wrote to the BOA urging it to review its policy.
But the BOA, which is the only national Olympic committee to enforce a lifetime ban for doping offenders, has repeatedly vowed to "vigorously defend" its selection policy.
BOA LIFETIME BANS
Sportsmen and women currently subject to the BOA lifetime Olympic ban include:
- Dwain Chambers (sprinting)
- David Millar (cycling)
- Carl Myerscough (shot put)
- Peter Meakin (canoeing)
- Jade Mellor (boxing)
- Callum Priestley (hurdling)
- Dan Staite (cycling)
- Jamie Stevenson (shot put)
- Kieren Kelly (shot put)
- Jatinder Singh Rakhra (wrestling)
In a statement, the BOA said the ruling had brought "clarity and closure" to its dispute with Wada, adding: "We look forward to receiving the formal findings from Wada setting out how they have determined the BOA's selection policy is non-compliant with the world anti-doping code."
Wada president John Fahey has defended the ruling and criticised BOA chairman Colin Moynihan for his claims that
current anti-doping sanctions are "toothless"
He said: "I'm very disappointed that it's come to this.
"I believe that Wada has acted very properly from the moment that we got news of the [Cas] decision.
"We had their decision conveyed to us through a vitriolic spray in a speech that was circulated to everyone except us earlier this week."