The Court of Arbitration for Sport (CAS) has issued a lifetime ban to a Russian doctor found guilty of breaking doping regulations. 

Dr Sergei Portugalov was working with athletes affiliated to the Russian Athletics Federation (RusAF), Monday's announcement the latest chapter in a long-running doping scandal involving Russia.

The nation were banned from competing in athletics at the Olympic Games in Rio last year, after a report commissioned by the World Anti-Doping Agency revealed widespread, state-sponsored doping.

"The Court of Arbitration for Sport (CAS) has issued its decision in the arbitration procedure between the International Association of Athletics Federation (IAAF), the Russian Athletics Federation (RusAF) and Dr Sergei Portugalov, a Russian medical doctor who advised athletes affiliated to RusAF," a CAS statement read.

"On the basis of clear evidence, Dr Portugalov is found to have violated the following articles of the IAAF Anti-Doping and Medical Rules: Article 32.2(f) ["Possession of a Prohibited Substance or Prohibited Method"], Article 32.2(g) ["Trafficking or Attempted Trafficking in any Prohibited Substance or Prohibited Method"] and Article 32.2(h) ["Administration or Attempted Administration of a Prohibited Substance or Prohibited Method"].

"As a consequence, a lifetime period of ineligibility, beginning on 10 March 2017, has been imposed on Dr Portugalov.

"The CAS acted as first instance decision-making authority for this matter, substituting for RusAF, which was suspended at the time the matter was ready to be adjudicated (and which remains suspended)."