'There's a cloud': Controversy erupts over 'impossible' athletics feat

Sifan Hassan said she is willing to undergo daily drug testing to prove she is a clean athlete after completing a stunning World Championship double on Saturday.

Just days after her coach Alberto Salazar was handed a four-year ban for doping offences, the Ethiopian-born Dutch runner surged to her second gold medal of the championships in the 1500 metres.

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Hassan's blistering winning time of 3min 51.95sec was the sixth fastest in history, and sliced around seven seconds off the 16-year-old championship record.

It came at the end of a tumultuous week for the 26-year-old Hassan, whose joy at a brilliant 10,000m victory last Saturday lasted only a few days before Salazar, her coach at the controversial Nike Oregon Project, was banned.

It’s the first time in athletics history that any man or woman has achieved the 1500-10,000m double.

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Salazar's downfall has cast a shadow over the entire Oregon Project training group, whose athletes have won three gold medals in Doha.

British runner Laura Muir, who finished fifth behind Hassan in the 1500m, said questions had to be asked.

“Given the news of the past couple of days, I think there is a cloud,” she said.

Hassan however hit back at the suggestion her performances should now be viewed with suspicion.

"If they want to test me they can test me every single day. Every single day," Hassan declared to reporters at the end of an impassioned press conference.

"I believe in clean sport, I'm always clean, I will always be clean. I believe in the Oregon Project. I've seen Alberto. He's worked really hard and that is what I know."

Hassan, who joined the Oregon Project at the end of 2016, pointed out she had been delivering consistent times throughout her career, which includes a World Indoor Championship gold medal in 2016.

'A constant athlete'

"I've been a top athlete since 2014," Hassan said. "I've won gold medals indoors, Diamond Leagues, I'm always a constant athlete."

Hassan, whose 2019 season has included a world record for the mile set in Monaco in July and four Diamond League victories, said she had been regularly tested throughout the year.

"Do people think if I cheat that I don't get tested? For five or six months when I'm running personal bests, that I don't get tested? For five years I've been a constant athlete."

Under international doping rules, Hassan was required to sever all contact with Salazar this week after the 61-year-old was banned.

She said Saturday she had formulated her own strategy for a masterful performance at the Khalifa Stadium, where she took the lead on the first lap and set the pace before kicking hard for home with about 250m to go.

“We’re witnessing something very special here,” one commentator said as Hassan was crossing the finish line.

“She’s done a double that most people thought would always remain impossible.”

Kenya's 2017 world champion Faith Kipyegon took silver while Ethiopia's Gudaf Tsegay bronze.

"I was so just angry and I could not talk to anyone. I just ran all out. That hard work can't be beaten by anything," Hassan said.

"It's what makes me angry, I have been clean all my life. I work hard. I'm not an emotional person but it makes me so mad."

Salazar was suspended for a catalogue of doping rule violations uncovered in a years-long investigation by the United States Anti-Doping Agency (USADA).

Hassan had emphasised in an earlier statement that Salazar's ban related to activities which took place before she joined the team three years ago.