Bantey Meanchey Provincial Governor Kosum Saroeuth yesterday called for an investigation of factors behind a Monday riot that saw military police resort to firing warning shots to dispel a rock-throwing crowd protesting taxes on cross-border trade in Poipet.

The order came after Ngor Meng Chhruon, the town governor, sent a letter to Saroeuth’s office. The letter accused a second deputy commune chief from the opposition Cambodia National Rescue Party and a unionist of instigating the protest by porters outside the local offices of the Customs and Excise Department.

However, in an interview yesterday, Saroeuth said the letter was just an informal report, and said it was too soon to point the finger at anyone.

“I think it’s just a report of the news. We cannot take any measure against any individual in the report without clear evidence,” he said. “However, the outbreak of violence at Monday’s protest was inspired by rabble-rousing information, and we need to look into the case closely in order to take legal action.

Poipet customs chief Chhuon Hai on Monday laid the blame at the feet of businessmen who hire the porters to transport goods across the border.

Chao Veasna, the second deputy commune chief accused in Chhruon’s letter, called the accusations against him an attempt to “slander and threaten”, saying he had only been at the demonstration in his official capacity as a commune official to observe the protest and bring it to a peaceful resolution.

“I would be thrilled to cooperate with all authorities involved in the investigation,” he said.

Meanwhile, the CNRP yesterday issued a statement calling for an independent and impartial investigation into the incident.

Monday’s violence saw at least three workers and a security guard injured as workers clashed with authorities, ultimately smashing down the gate to the customs office, and breaking much of its glass facade with rocks and bricks. According to a daily customs report, Governor Saroeuth said, the lack of goods crossing the border due to the protest cost the customs bureau more than $375,000 in revenue.

One porter participating in the protest, Mao Son, was badly beaten by police and ultimately hospitalised. According to his wife, Vann Sreymom, a porter as well, Son is recovering, and authorities came yesterday to remove a pair of handcuffs they only partially applied during an attempt to arrest him.

Porters have protested before against what they consider excessive customs rates. According to Sreymom, scanners installed late last year mean that customs officials are able to precisely calculate the amount of customs tax owed, causing taxes to rise sharply – particularly for shipments including more expensive goods that had previously not been properly taxed according to their value.

Businesspeople, she said, pay the porters a flat rate to move goods across the border, with the tax bill coming out of the porters’ fee. However, they have been unwilling to raise rates in tandem with customs fees, prompting the workers to seek a lowering of the rates, she added.

Customs head Chhuoun Hai on Monday called on protesters to help officials identify the owners of the goods so the burden of the taxes would be shifted to them.