Arsenal and Chelsea have both issued responses to suggestions that some of their players have been involved in doping.
Dr Mark Bonar, who works at a private clinic in London, was secretly filmed by The Sunday Times claiming that he had prescribed banned substances to 150 sport stars, some of whom represented the London duo.
However, the pair have released statements in which the allegations are branded "false" and "baseless".
"Arsenal Football Club is extremely disappointed by the publication of these false claims which are without foundation," said the Gunners.
"The Sunday Times knows that these allegations are baseless but has preferred to publish regardless.
"The club takes its responsibilities in this area very seriously and our players are well aware of what is expected. We strictly adhere to all guidelines set by the World Anti-Doping Agency."
Meanwhile, the Blues added: "The claims The Sunday Times put to us are false and entirely without foundation.
"Chelsea Football Club has never used the services of Dr Bonar and has no knowledge or record of any of our players having been treated by him or using his services.
"We take the issue of performance enhancing drugs in sport extremely seriously and comply fully with all anti-doping rules and regulations. Chelsea FC players are regularly and rigorously tested by the relevant authorities."
Dr Bonar also claimed that players from Leicester City and Birmingham City had sought his help.
