Three Ethiopian runners have been suspended on suspicion of doping amid a string of positive tests among the country's athletes, track and field officials said on Friday.

Ethiopia's national track team doctor called the East African nation's growing doping scandal "a very terrifying development."

Three athletes were formally suspended and another three are also under investigation, Ethiopia Athletics Federation secretary general Bililign Mekoya said at an anti-doping awareness event in Addis Ababa. Bililign and other officials did not give the names of the athletes, citing ongoing investigations.

Track and field's world governing body, the IAAF, is also investigating a number of Ethiopians for doping.

The sport is now facing serious doping problems in Ethiopia following major scandals in Russia and Kenya in the run-up to this year's Olympics in Rio de Janeiro. The Ethiopian Anti-Doping Agency told The Associated Press this week that at least nine athletes were under suspicion, with some being investigated in Ethiopia and some by the IAAF.

Some of those athletes under investigation were "top athletes," a senior official with the anti-doping body told the AP.

Speaking at the same event alongside Bililign on Friday, national team doctor Ayalew Tilhaun said Ethiopians recently tested positive for steroids, testosterone, the stimulant ephedrine, and the diuretic furosemide, among other banned substances. Ayalew wouldn't identify the athletes because investigations are ongoing.

"We are witnessing a very terrifying development here," he said.

One runner, Sintayehu Mergia, identified himself as one of the athletes under suspicion by speaking on a local radio station. He denied doping.

This week, the IAAF announced that Ethiopian-born former 1,500-meter world champion Abeba Aregawi had failed an out-of-competition doping test. Aregawi, who now competes for Sweden, was tested in Ethiopia, Swedish media said. Ethiopia's 2015 Tokyo Marathon champion, Endeshaw Negesse, has also been linked to a failed doping test in media reports.

Ayalew, the team doctor, said evidence indicated that athletes were paying $900 to get a dose of banned substances in Ethiopia. Two foreigners, one a Turkish national, were implicated in providing the banned substances, Ayalew said, and were under investigation.

The World Anti-Doping has instructed Ethiopia's athletics officials to implement strict measures to improve their anti-doping program.

Ethiopia's case is reminiscent of East African neighbor and fellow distance running power Kenya, which has seen a big surge in doping cases in the last few years as a result of lackluster anti-doping controls.

Kenya is facing a possible suspension from international competition if WADA decides that it has not brought its program in line with global anti-doping rules. Russia was suspended by the IAAF last year after a WADA-commissioned report found evidence of a vast system of doping and cover-ups.

Kenya and Ethiopia collectively won 24 medals at the world championships in Beijing last year.