The president of Sri Lanka has said foreign judges and prosecutors should not be involved in an investigation into allegations of war crimes.
In a BBC interview, President Maithripala Sirisena said the country did not need to "import" specialists.
Both the army and the Tamil Tiger rebels are accused of atrocities in the civil war that ended in 2009.
The government previously backed a UN resolution calling for a war crimes court supported by foreign judges.
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."
In October 2015, Sri Lanka co-sponsored a UN Human Rights Council resolution calling for a special judicial mechanism to prosecute war crimes to be established - with support from Commonwealth and foreign judges, prosecutors and investigators.
As many as 100,000 people are thought to have died in the Sri Lankan civil conflict.
The final months of the 26-year war were the most bloody, with the government accused of repeatedly shelling safe zones set up to protect civilians. The Tamil Tiger rebels were accused of holding civilians as human shields and firing on those who tried to flee. Both sides denied the allegations.
President Sirisena said that while the UN report released in September 2015 had pointed to army involvement in war crimes, the report had failed to mention names. He said it was important to determine whether such crimes actually took place.
He said: "If the Sri Lankan Army is alleged for such crimes, our concern should be to free them from those allegations. If anyone has committed a crime, there's no doubt that they should be punished. However it is wrong to make the entire army guilty for what happened."
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 some one can prove with evidence, I am ready to give them the opportunity. Justice is served equally in this country."