A Myanmar journalist was killed in military custody in early October after he was detained while covering clashes between the army and ethnic Karen separatists.

Aung Kyaw Naing, also known as Pary Gyi, was detained Sept. 30 and was shot and killed Oct. 4, media outlets including the Thailand-based Irrawaddy said, citing the country’s interim press council. Naing’s death was not announced until Oct. 24 and no explanation was given for the delay in reporting it.

The army accused Naing of working as an information officer for a Karen rebel group and said he tried to grab a guard’s gun and was shot while attempting to flee, the Associated Press reported, citing the information the press council had obtained from the military. Naing’s body was buried by the military in a remote village in the country’s southeastern Mon state. A spokesman for the rebel group, the Klohtoobaw Karen Organization, denied that Naing was part of the organization, the Irrawaddy said.

Naing had reported for Myanmar outlets including The Voice, Yangon Times and Eleven Media, the Committee to Protect Journalists said.

“The killing of Aung Kyaw Naing by Burma’s military is reprehensible,” said Shawn Crispin, CPJ’s Southeast Asia representative, in a statement. “Civilian authorities must investigate the military’s accounting of his death, which has the initial hallmarks of a cover-up. Any soldier found responsible for his extrajudicial killing or mistreatment before his death must be prosecuted to the fullest extent of the law.”