Military personnel and police officers stand guard before a crime re-enactment near the bomb site at Erawan Shrine in Bangkok, Thailand, Sept. 26, 2015. REUTERS/Athit Perawongmetha

Thailand has dropped criminal charges against a Hong Kong photojournalist who was arrested after he was found in possession of personal body armor last year, a move that was welcomed by international press groups, reports said Wednesday.

Hok Chun Anthony Kwan, 30, was detained at Bangkok's airport in August as he was leaving the country after completing an assignment to cover the bombing of Erawan Shrine that left 20 people dead and injured 125 others.

Body armor is prohibited without a license under Thailand's strict Arms Control Act, but is a common article for journalists sent to cover dangerous places. Kwan, who works for Hong Kong-based Initium media group, holds Hong Kong and Canadian passports.

Kwan was later released on bail, but authorities had confiscated his travel documents and told him not to leave the country for further investigation.

His passport was later returned following calls from the Committee to Protect Journalists and Reporters Without Borders, which criticized the arrest and spearheaded calls for his freedom. Kwan, who was required to return to Bangkok every 12 days to check in with authorities, was formally charged in October.

While the crime is punishable by up to five years in jail, it has never been enforced against journalists covering Thailand's often volatile political landscape over the past decade.

Kwan pleaded not guilty to the charges, and his lawyer Pawinee Chumsri, after being contacted by the Bangkok Post, confirmed Tuesday that his case had already been dropped.

The Foreign Correspondents' Club of Thailand, in a statement, welcomed the development, but called on authorities to help find a way for journalists to do their work in dangerous environments.

Vests, such as the one found on Kwan, were a "required and essential equipment for journalists working in conflict zones," it said.