Vladimir Putin has insisted Russia has "never supported any dopers" in the wake of allegations it operated a state-sponsored doping programme that sabotaged the London 2012 Olympics.
The president's comments came after international athletics bosses meeting in Vienna decided not to lift the ban on Russia's athletics federation in time for the Rio Olympics.
Despite desperate Russian attempts to have the ban lifted before the August Olympics, the International Association of Athletics Federations' 27-strong council decided Russia had not met the criteria for reinstatement.
Russia has been suspended from international competition since November after an investigation commissioned by the World Anti-Doping Agency (Wada) uncovered systematic cheating.
The Wada report uncovered a "deeply-rooted culture of cheating" and said samples had been destroyed and bribes paid to cover up the scam.
Asked about the allegations in a panel discussion at the St Petersburg International Economic Forum, Mr Putin said: "At the state level, we have been fighting doping in the sport and we will continue doing that."
He added: "Anyway, the law enforcement agencies have to treat all the violators in the same way, this is our position. We are going to work in this way in our fighting against stimulants and dopers, and we are going to work with fans' associations.
"And I believe there are many sensible people among the fans who realise that any violations cannot express their support for the team they love - any violations only jeopardise the teams they support.
"But I realise that we still have a lot to do in this area. But let me emphasise that we have never supported any violations in sport, we have never supported it at the state level, and we will never support this.
"We will never support any dopers or any other violations in this area, and we are going to co-operate with all the international organisations in this regard."
He added: "I thought that if samples are taken they are always removed for storage to the international organisations and we do not affect them in any way.
"They are never stored in the territory of the Russian Federation, they are going to some other city. They can be reopened and rechecked and I believe the experts are doing that at the moment."
He insisted that doping is not only a problem in Russia, but blights many countries and teams.
And he suggested that if anyone has been caught doping they are individually responsible and there should be "no collective responsibility for all athletes of a country".
He said: "The doping problem is not only related to Russia, it is the problem that is relevant for the whole sports world. And if someone is trying to politicise this area it is a big mistake.
"The sports area cannot be politicised, sport is a bridge that brings people and states together and this is the way we have to approach it. This cannot be a foundation for building anti-Russia policy, or a policy against some other country.
"And I can tell you with full responsibility that we are against any doping in Russia."
Mr Putin, a keen sportsman who has been photographed playing ice hockey and riding topless on a horse in Siberia, said doping undermines the sport and endangers athletes.
He said: "I have been an amateur athlete and I believe that many people will agree with me when I say that if doping is used it is much less interesting to watch such competitions. The sport becomes less interesting for millions of spectators.
"And the second aspect that is very important is the health of athletes, because nothing can justify the harm that is brought to the human body."