CHUNCHEON, South Korea, June 23 (Yonhap) -- Police said Thursday that they have cleared a marathon coach and his athletes of doping allegations, wrapping up their probe two months before South Korea hosts the world athletic championships.

The Gangwon Provincial Police Agency said it has examined records from a rehabilitation hospital where 19 athletes were treated, and found no evidence that they had been injected with banned substances to enhance their performance.

Among the athletes under investigation was Ji Young-jun, a top local marathoner who won the gold medal at the Guangzhou Asian Games last November. Ji trained under the 51-year-old coach, Jeong Man-hwa.

"The athletes said they took iron supplements as part of their rehabilitation treatment, denying that it was aimed at enhancing their performance," an official at the police agency's narcotics unit said. "We couldn't find evidence to prove the allegations, because the iron supplements we confiscated did not contain banned substances."

The investigation came before the southeastern city of Daegu hosts the 2011 World Championships in Athletics slated for August.

South Korea has never won a medal at the world championships, and the marathon is regarded as the host's best chance for a medal.

The Korea Association of Athletics Federations (KAAF) had earlier launched an internal probe, but it also found no evidence of doping. KAAF officials suspected some coaches of semi-pro clubs may have conspired against Jeong and given false tips to police.

In a statement, the KAAF said it "humbly accepts" the police findings and apologized to the public for causing them concern.

"From now on, we will shift our focus back on preparing for the world championships," the statement said. "We will try to return all the love and support from our fans."

Through the association, Jeong thanked his supporters for sticking with him. Ji said he will let his performance at the world championships speak for itself.

KAAF President Oh Dong-jin lamented the distraction caused by the incident, which also cut into training time for the athletes.

He said he will urge athletes and coaches to be more vigilant about avoiding banned substances and that he will spare no effort to support athletes any way he can until the championships.

Oh also vowed to take action against those who falsely accused the marathon coach and athletes.

"As for those who targeted national athletes for defamation, for the sake of their own interest, I will hold them accountable," Oh said.