9:21 AM PT -- The International Skating Union says it has investigated the allegations ... and found "no evidence" Mariah Bell intentionally attacked Lim Eun-soo.

"The incident was verbally reported to the ISU by the Korean Team Leader however no formal complaint has been received," The ISU said in a statement.

"Based on the evidence at hand at this point in time, which includes a video, there is no evidence that Ms. Bell intended any harm to Ms. Lim."

"The ISU met with delegates from both USA and Korea and urged both parties to find an amicable solution. The ISU maintains that this remains the appropriate approach."

A 16-year-old female Korean figure skater is calling for an investigation -- claiming her 22-year-old American rival intentionally SLASHED her with her skate during warm-ups at a major event.

Reps for Lim Eun-soo claim the 16-year-old was at the ISU World Figure Skating Championships in Japan on Wednesday ... when Mariah Bell came crashing into her from behind, leading with her skate.

Eun-soo's agent described the incident this way to Agence France-Presse:

"Lim was slowly skating on the edge of the rink after completing her turn. Mariah Bell, who was scheduled to rehearse after Lim, suddenly kicked and stabbed Lim’s calf with her skate blades."

"Mariah Bell didn’t apologize to Lim Eun-soo after the incident and instead continued to rehearse for her routine."

Eun-soo reportedly suffered a gash on her calf which required medical attention. She was able to treat the wound and still compete ... ultimately finishing in 5th place, one spot AHEAD of Bell.

Lim Eun-soo's agent told the French media they have already gone to the Korea Skating Union and asked for a formal investigation.

Eun-soo's agent also says the two skaters have been training in Los Angeles together -- and they claim Bell has been "bullying" their client for months.

So far, no comment from Bell.