" The United Nations has repeatedly called for investigations into alleged rights abuses and war crimes said to have been committed in the last weeks of fighting that culminated in May with the killing of the top rebel leadership.
Sri Lanka has resisted calls for any investigation, saying no civilians were harmed by government forces in its fight.
Sri Lanka insists it carried out a "humanitarian operation" to free Tamil civilians from rebel control.
However, the United Nations has reported that at least 7,000 civilians perished during the last four months of fighting, with many more wounded.
The UN has also accused Tamil Tigers of holding civilians as human shields. President Mahinda Rajapakse views Ban's plan for the panel to advise him on "accountability issues" involving the final phase of fighting with Tamil rebels last year as interference in Sri Lanka's internal affairs, his office said.
Rajapakse was "emphatic" in his objections when Ban, in a telephone conversation Friday,