Cambodia’s detained opposition leader, who is accused of treason by the government of strongman Prime Minister Hun Sen, denied the charges against him on Monday in his first comments since his arrest last month.

Kem Sokha, head of the opposition Cambodia National Rescue Party (CNRP) is accused of trying to overthrow the government with help from the United States and of espionage – charges he denies and says are politically motivated.

His arrest last month is part of ongoing efforts by the government to silence political opponents and independent media ahead of a general election next year.

Earlier on Monday Hun Sen, a former Khmer Rouge officer who defected and has ruled Cambodia for more than three decades, attacked opposition figures as “rebels in the city” bent on staging a revolution.