PHNOM PENH, Nov. 20  -- Cambodian Prime Minister Hun Sen said Thursday that he and his government have no rights to order the courts to arrest or release any suspects who have committed crimes.

"I and the government have no rights to order the judiciary, the court to arrest anyone based on evidence of offenses," he said, referring to the last week's arrest of 15 land activists and opposition officials.

"Everything has to follow the law," he said at a graduation ceremony of 1,200 students at the IIC University of Technology.

"Democracy and the rule of law must be simultaneously strengthened," he said, adding that there would be no more tolerance for protesters blocking roads during protests.

Hun Sen's remarks came after critics and a United Nations envoy accused the Cambodian government of using the judiciary to silence the opponents.

In the past week, the Cambodian authorities arrested 15 people, including 13 land activists and two opposition officials. Eleven activists have been charged with illegally blocking a road and obstructing public officials during their protests and sentenced to one year in prison each.

While the two opposition officials were apprehended in accordance with court warrants for their alleged involvement in leading an insurrection over a violent clash during a protest near the Freedom Park on July 15.

Surya P. Subedi, UN Special Rapporteur on the situation of human rights in Cambodia, on Tuesday criticized the Cambodian government for a series of arrests, alleging that the government is using the judiciary to silence critics and opposition officials.