Moscow?- Russian four-time breaststroke world champion Yuliya Efimova has been suspended from competition over alleged doping, Russia's swimming federation said Thursday, with media reporting she faces a life ban for using meldonium.

Russia's Yuliya Efimova has won four breaststroke gold medals at the world championships.?[Photo/Agencies]

Russia's swimming federation confirmed that it had received documents from the sport's governing body "confirming the temporary suspension of the sportswoman from competition in connection with a possible doping rule violation".

Russian media reported that 23-year-old Efimova -- who won a bronze medal at the London Olympics and trains in the United States -- faces a life ban after becoming the latest athlete to test positive for meldonium, a substance banned on January 1.

This could be a repeat violation, as she was banned for 16 months after failing a test for a banned steroid in October 2013.

The news of the suspension came as Ukraine's athletics federation on Thursday said 800-metre runner Natalya Lupu would not compete at the 2016 indoor world championships for also using meldonium.

"WADA has some questions related to the use of meldonium for Natalya Lupu," the federation said in a statement.

"In connection with this it was decided to cancel Natalya Lupu's trip to the Portland world championships."

Russian tennis star Maria Sharapova admitted earlier this month that she had tested positive for meldonium at the Australian Open in January.

The World Anti-Doping Agency (WADA) said last week that 99 athletes worldwide had tested positive for the drug since the ban came into force at the start of the year.

Meldonium is manufactured in Latvia and prescribed to treat heart disease.

The drug is available as an over-the-counter medication in many parts of eastern Europe but not approved for use in the United States by the Food and Drug Administration.

Russian President Vladimir Putin on Wednesday blasted sports officials in the country for failing to warn athletes in time that meldonium had been added to the list of banned substances.

Russian track and field is currently battling a separate doping scandal that has seen the the team suspended from competition over claims from WADA last year of state sponsored doping in the sport.