The Rugby Football Union has vehemently rejected claims by French coach Bernard Laporte that English rugby may not be drug-free.
Laporte will step down as France coach after the World Cup
Laporte said France has tight doping rules, but he "could not be sure" about players in England or New Zealand.
"We're confident we have a very robust programme," RFU tournaments director Terry Burwell told the Daily Mail.
"We're the only Union with a full-time doping officer, which leaves no doubt as to how seriously we take it."
The RFU's doping chief is Gavin Dovey, appointed in December 2006 having previously worked for the Australian Sports Anti-Doping Authority.
In the 2006-07 season, 414 tests were carried out on rugby players in England under the RFU's testing programme, with over 50% conducted out of competition with no advance notice.
In total that season, 460 players in England were tested, with only two positive results, both for the presence of a prohibited substance in a player's sample.
Burwell said UK Sport's testing programme supplemented the RFU's own efforts.
"UK Sport conducts 450 tests on our behalf every year, both after matches and at random, in and out of season," said Burwell.
The response came after Laporte queried the cleanliness of English rugby.
"There is regular monitoring in France," said the French coach.
"The player cannot dope himself - well, he can, but he will be caught. But what is happening in New Zealand or in England? You cannot be sure of anything.
"The only certainty is there are dope tests at international matches. But they are only on urine and you have to go further than that."
International Rugby Board vice-chairman and ex-England captain Bill Beaumont has also rejected Laporte's comments out of hand.
"The RFU - and rugby in general - takes drug-testing extremely seriously," he told Radio Four's Today programme.
"Certainly from the RFU's point of view, I think they act in a very diligent manner regarding testing.
"I'm surprised and disappointed (by Laporte's comments)... Whether it was taken out of context, I don't know."