Mutu spent the weekend with his ex-wife, Alexandra, in Italy, missing the club's 1-0 defeat at Manchester City on Saturday.
Andrea Pretti, another representative of Mutu, added: "The player is in London - he had spent a couple of days in Italy but he's returned to the English capital.
" We are awaiting the counter-analysis. We don't think it will take long for things to happen, possibly a couple of days. You can imagine how the player feels.
"He already had technical problems at Chelsea and now this has just made it even worse. Until this situation is cleared up his future will is secondary."
Even before news of the positive test broke, Mutu, a £15.8million signing from Parma, looked set to be on his way out of the club. He was fined two weeks' wages of £120,000 for having a row with Mourinho last week.
UK Sport, which carried out the test on Mutu, refused to confirm whether the player had failed a test. So far, it is believed Mutu has had only his A sample tested.
He can now request that his B sample, collected at the same time as the A sample, is tested.
Although out-of-competition tests for social drugs do not carry the maximum two-year ban under the World Anti-Doping Agency code, the FA can ban players for six months if they refuse rehabilitation.
