Matt Stevens faces an uncertain future with Bath after chief executive Bob Calleja admitted he and the club felt shocked and let down by the prop's failed drugs test.

England tighthead Stevens admitted on Tuesday he had tested positive for a banned recreational drug, adding that he has a problem with a "very serious substance", understood to be cocaine.

The 26-year-old, who is one year into a four-year contract at Bath, failed a random post-match test after his side's victory at Glasgow last month.

And Calleja said on Wednesday that Stevens' actions had overshadowed the build-up to Sunday's winner-takes-all Heineken Cup pool finale against Toulouse at the Recreation Ground, Bath's biggest match of the season so far.

"These are obviously very difficult circumstances," said Calleja.

"This week should have been all about the anticipation of a classic winner-takes-all match at the Rec. Instead, of course, the headlines are going to be dominated by Matt Stevens.

"The facts are these: we were informed by ERC, the Heineken Cup organisers, on Monday evening of this week that Matt had failed a drugs test of a sample taken from the Glasgow match on December 14.

"As soon as I got that call, we immediately got in touch with Matt. He was in London but I spoke to him on the phone, and in accordance with the IRB suggestions, suspended the player. The suspension will remain in force until the disciplinary process – as laid out in the ERC competition regulations – has been completed.

"On Tuesday, Matt was interviewed by Sky Sports and admitted to taking a banned recreational substance, consistent with the findings of the drugs test.

"Matt remains suspended from the club pending the completion of the disciplinary process. Clearly this is a very serious matter. The club does not and will not condone the use of illegal recreational or performance-enhancing drugs by any of its employees.

"But it must also ensure that the disciplinary process is fairly conducted and then allowed to reach proper conclusion as the case is resolved. Only then, when all the circumstances and facts are known, will we make a further statement to the public."

Stevens arranged the interview he gave to Sky Sports without his club's permission – and Calleja said he was shocked by both the findings of the drugs test and the content of his player's interview.

"I was absolutely shocked," he said. "It was devastating news. With all the problems we are facing at the club – in terms of the Recreation Ground development and the recent rearranged game (against Wasps) – this was yet another shock that we certainly could have done without.

"I think we all feel let down – he has a responsibility. But until all the circumstances are known, I'm not going to comment any further than that."

Head coach Steve Meehan is the man charged with ensuring the other members of the Bath squad remain focused ahead of Sunday's Pool Five decider – a match Calleja remains confident his players will win.

"I know the team are remaining focused," said the chief executive. "They realise the importance of the game. How distracting it will be will tell at 5pm on Sunday, but we're going to beat Toulouse."

Meehan, meanwhile, is backing Stevens' replacement, Duncan Bell, to produce the performance of his career against the French champions.

The 34-year-old England prop was particularly effective when starting the recent narrow defeat at Leicester and Meehan has every confidence in him.

"Our focus has got to be on Sunday afternoon – it must be," said Meehan. "And I think we will see the greatest performance from Duncan Bell since he returned from his injury. This is a fantastic opportunity for him personally and I expect to see something special from him."

Stevens, who has been given a provisional ban from all rugby, has seen his place in England's Six Nations Championship squad taken by Leicester's former Bristol tighthead Julian White.