Sri Lanka's pro government "Island" newspaper published some parts of the UN report.
Full report expected to be released in a few days.
Latest AP report:
A U.N. panel has called for a thorough international investigation into allegations that war crimes were committed in Sri Lanka as its decades-old civil war drew to a close nearly two years ago.
A copy of the three-member panel's report was printed Saturday in The Island newspaper. It says there are credible allegations that Sri Lankan soldiers and Tamil Tiger rebels committed serious violations, including some which could amount to war crimes.
The U.N. spokesman's office said it was "deeply regrettable" that the report had been leaked before its official release next week.
The panel gathered evidence for 10 months and submitted its report to U.N. Secretary-General Ban Ki-moon this past week.