LAUSANNE, Switzerland - The head of the World Anti-Doping Agency (WADA) said on Tuesday he remained sceptical and concerned about Russia's anti-doping practices as some of the country's athletes prepare to compete as neutrals at this year's Paris Summer Olympics.

Speaking at the WADA Annual Symposium in Lausanne, WADA President Witold Banka said he had received many questions from concerned athletes regarding the Russians who could be competing in Paris.