The Court of Arbitration for Sport has levied a lifetime ban against a Russian doctor found guilty of breaking doping regulations.

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

The nation was banned from competing in track and field at the Rio Olympics last year, after a report commissioned by the World Anti-Doping Agency revealed widespread, state-sponsored doping.

"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)."