Cambodia's prime minister is suing the country's opposition leader and an opposition lawmaker for suggesting the authorities were involved in the killing of a popular political analyst who spoke critically of the government.

Legal papers filed Monday with the Phnom Penh Municipal Court show that a lawyer for Prime Minister Hun Sen is suing Cambodia National Rescue Party leader Sam Rainsy for defamation for remarks he posted on Facebook linking the authorities to the July 10 killing of Kem Ley. His party colleague Thak Lany was sued for making similar allegations in a speech.

The government last year began cracking down on the opposition through the courts, which are considered tools of the ruling party. Sam Rainsy has stayed in exile to avoid a prison term in another defamation case.