The BBC Panorama programme "Catch Me If You Can" claimed US coach Salazar violated various anti-doping rules and used testosterone medication on Galen Rupp in 2002 when he was 16.
Both men deny all the claims.
The BBC understands that US Anti-Doping Agency (Usada) is also investigating the allegations.
London 2012 10,000m silver medallist Rupp is training partner of Great Britain's Mo Farah. Both athletes are part of Salazar's Nike Oregon Project.
There are no suggestions Farah has been involved in any doping.
Ukad chief executive Nicole Sapstead said the body would only publish the outcome of any prosecution.
"As with all of our ongoing investigations, Ukad will not disclose any details, to protect the privacy of everyone involved, and so we do not undermine our own operations of deterring and detecting doping in sport," said Sapstead.
