The Human Rights Party on Tuesday threatened to hold mass demonstrations if the government is unable to allay rising prices for fuel and other commodities, echoing a similar call from the Norodom Ranariddh Party.
The price of gasoline has nearly tripled this year, putting a heavy burden on some of Cambodia's poorest, while the prices of other goods continue to rise.
Poor regulation from the government in keeping costs down has added to the problem, the Norodom Ranariddh Party said in a statement demanding the Ministry of Finance act.
Gasoline prices have risen to 4,400 riel per liter, more money than many impoverished Cambodians earn in a day.
The Human Rights Party said it would hold demonstrations if the government did not lower taxes on imported fuel. Taxes on harmful substances like cigarettes and alcohol could be raised instead, the party urged.
Neither government spokesman Khieu Kanharith nor Finance Minister Keat Chhon could be reached for comment Tuesday.
Fuel company magnate Sok Kong said oil prices were high globally, leading to the high prices in Cambodia.
"Now you want me to reduce the price?" he said. "How can I reduce it? Now the price is how it is. I am not the only one. It's the whole world."
Economist Kang Chandararoth said the only way to lessen the impact of high fuel prices was to work to lower the costs of other goods.