AFP/Bangkok

A Hong Kong photographer detained for carrying a bullet proof jacket and helmet in Thailand will face trial after pleading not guilty to a weapons possession charge on Monday.

The case has sparked outcry from media freedom groups who say journalists should not be punished for carrying body armour and protective gear in and out of dangerous zones.

Kwan, who works for the Hong Kong-based Initium media group, was held on August 23 after trying to depart Bangkok's Suvarnabhumi airport with a flak jacket and helmet in his hand luggage.

But both items are classified as weapons under Thai law and Kwan was charged with breaching the country's Arms Control Act -- punishable by five years in jail.

He was in Thailand to cover the aftermath of August's deadly Bangkok bombing.

Kwan told reporters on Monday after the hearing at the Samut Prakhan provincial court, near Bangkok, that he had been indicted.

"I'm not confessing... I don't think that a flak jacket is a weapon and I definitely didn't know it was illegal here."

His plea means he will face a trial starting next month. The court granted Kwan bail but was set later Monday to rule on whether he is free to leave Thailand.

"I think everyone in my situation would be a little bit concerned. I'm preparing for the worst but hoping for the best," Kwan added.

Thailand's classification of protection equipment as a weapon that requires a license has been criticised by media groups who say they are vital pieces of kit for reporters in a country where political violence routinely spills onto the streets.

Ahead of Monday's hearing, the Foreign Correspondents' Club of Thailand issued a statement to express disappointment at Kwan's indictment.

"Thai authorities should consult with the media community... to explore a way around the 1987 law, which was surely not intended to prosecute journalists carrying out their normal duties," the statement said.