The trio, employees of Puma supplier Kaoway Sports, were wounded after a gunman opened fire on a protest in February demanding better working conditions at factories in eastern Svay Rieng province.

Chhuk Bundith, governor of Bavet City at the time of the shooting, was charged in April with causing unintentional injuries and removed from his post.

"The court has dropped all charges against him," the victims' lawyer Chin Linda told AFP, adding the court has instead charged a police officer with involuntary bodily harm over the incident.

The decision dismayed rights campaigners who have long criticised the country's culture of impunity.

Ou Virak, president of the Cambodian Centre for Human Rights, said he was "disgusted at the level of impunity" in Cambodia, adding Puma would have to re-think their investment in the country.

Local rights group ADHOC said the court decision highlighted the "disregard for the rule of law" in Cambodia, which could hurt the nation's reputation as a hub for the garment trade -- which employs 300,000 people, mostly women.

Court officials could not be reached for comment.

Victim Bout Chinda, who spent two weeks recovering after a bullet pierced her lung, said she was frustrated with the ruling and vowed to fight for justice.

"I was shot from behind. Many people saw Chhuk Bundith open fire," the 21-year worker told AFP, adding she was left "speechless" by the decision to drop charges and would continue to fight for justice.

Retail giants Puma, Gap and H&M have all voiced deep concern over the incident and urged Cambodia to fully probe the shooting.

In an emailed statement to AFP on Tuesday Puma said it does not comment on political or judicial issues but urged the Cambodian government to "put all efforts into convicting the guilty perpetrator".