President Maithripala Sirisena says foreign judges and prosecutors should not be involved in an investigation into allegations of human rights violations.
In an interview with the BBC, the Head of State said the country did not need to “import” specialists.
But on Thursday the president said: "I will never agree to international involvement in this matter." "We have more than enough specialists, experts and knowledgeable people in our country to solve our internal issues," he said.
"This investigation should be internal and indigenous, without violating the laws of the country, and I believe in the judicial system and other relevant authorities in this regard. “The international community need not worry about matters of state interest."
Asked when the court might be set up, he said: "These things cannot be done instantly or in a hurried manner.
"We will certainly reach our target but it's a process."
The president also dismissed reports from the advocacy group Freedom from Torture that people in detention were still being tortured.
Saying the claims were made by people who were close to the Tamil Tigers, President Sirisena added: "I totally deny that. If someone can prove with evidence, I am ready to give them the opportunity. Justice is served equally in this country."