Two unnamed Russians who play for the national women's and men's sevens teams have been suspended for taking the banned substance meldonium, the country's rugby federation (RRF) said on Friday.

"A player from the men's rugby sevens national team admitted the results from his A sample and rejected the opportunity to test his B sample," the RRF added in a statement.

"A sportswoman from the women's rugby sevens team says she has not taken any illegal substances and has asked for her B sample to be tested."

GETTY IMAGES Maria Sharapova reveals she has been taking the drug meldonium for the last 10 years.

Meldonium was added to the World Anti-Doping Agency's list of banned substances on January 1.

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Eight other Russian sportsmen and women have been found to have taken meldonium including former world number one tennis player Maria Sharapova.

The remaining seven are biathlete Eduard Latypov, cyclist Eduard Vorganov, figure skater Ekaterina Bobrova, speed skater Pavel Kulizhnikov, short-track speed skaters Semion Elistratov and Ekaterina Konstantinova and the volleyball player Alexander Markin.

Rugby sevens will be making its Olympic debut in Rio de Janeiro in August.

The Russian men's and women's teams must still go through final qualifying tournaments in June to book a place at the Brazil Games.

Meanwhile a Rio Olympic athletics programme without Russia looks an ever-stronger possibility after the sport's governing body said on Friday that the athletics superpower had "significant work to do" to have any chance of having its ban lifted in time.

Norwegian Rune Andersen, heading a five-person task force reviewing Russian reforms after November's suspension from global competition, said Russian athletics had made "significant progress", including changing its president and council and developing anti-doping educational programmes.

"However, the view of the task force is that there is significant work still to be done to satisfy the reinstatement conditions," he told a news conference after a Monaco meeting of the Council of the International Association of Athletics Federations (IAAF).

"We still need to interview athletes and coaches named in the WADA (World Anti-Doping Agency) commission report to understand the scope and nature of previous doping activities."