Dwain Chambers will be subjected to additional drugs tests while he is with the Hamburg Sea Devils.
Former Balco chief Conte, right, claims he now supplies Chambers with legal nutritional supplements
Chambers is making a career as a wide receiver in Germany after serving a two-year athletics ban for using drugs.
But an NFL Europe spokesman told BBC Sport: "Because of his background he is liable for additional testing."
It comes in the wake of claims that Chambers is still in touch with Victor Conte, who supplied him with the anabolic steroid THG three years ago.
Conte, who served four months in prison in 2005 for supplying athletes with performance-enhancing drugs, is back in the business of selling nutritional supplements from his old Balco offices under a different name, SNAC.
And he claims he is again supplying Chambers, 27, with supplements, though he insists they are perfectly legal.
Whoever Mr Chambers has contacts to, as long as it does not affect his professional commitments, then we will not comment
NFL Europe communications director
"Dwain got caught up in something he shouldn't have been involved in. I mean this kid made mistakes and he came forward," Conte told the Guardian.
"Now he takes Proglycosyn, he takes ZMA, he takes Aerobitine [all SNAC products]. But there is nothing illegal in this stuff, it is simply beneficial from a nutritional point of view."
That claim was originally denied by Chambers in a statement through a Sea Devils spokesman, but when asked to comment by the BBC, the Sea Devils declined.
NFLE director of communications Maik Matischak, though, said: "Whoever Mr Chambers has contacts to in his private life is his private and personal decision, and as long as it does not affect his professional commitments to and contract with NFL Europe, then we will not comment.
"The NFL Europe and the Sea Devils will not comment on Chambers' past. He is a player of the NFLE now and we will only talk about his performance on the field."
However, he added: "All of our players are subject to the NFL's drugs testing policies and procedures, which is among the most stringent in any sport."