The publication of a United Nations report on alleged war crimes committed during the protracted civil war in Sri Lanka has been postponed till September, according to a statement released by the U.N. Human Rights Council (UNHRC) on Monday. The report, which contains details of atrocities committed by the Sri Lankan army and the Tamil separatist group LTTE, was originally scheduled to be released in March.

“This has been a difficult decision,” U.N. High Commissioner for Human Rights Zeid Ra’ad Al Hussein said in the statement. “There are good arguments for sticking to the original timetable, and there are also strong arguments for deferring the report’s consideration a bit longer, given the changing context in Sri Lanka, and the possibility that important new information may emerge which will strengthen the report.”

However, Al Hussein did not specify what the new information is and how it might become available. 

The nearly three-decade civil war in the island nation had pitted the majority Sinhalese population in the country against the LTTE, a separatist group demanding a separate homeland for the minority Tamils. Up to 100,000 people, including a huge number of civilians, are believed to have died in the conflict. The war ended after the Sri Lankan military killed LTTE leader Velupillai Prabhakaran in 2009.

Both sides have since been accused of indulging in widespread human rights violations. The UNHRC said last year it would investigate the alleged war crimes but Sri Lanka’s former President Mahinda Rajapaksa, who was defeated by his one-time ally Maithripala Sirisena in January, refused to cooperate. The new government has promised to cooperate with the U.N. inquiry, according to media reports.

“I have received clear commitments from the new Government of Sri Lanka indicating it is prepared to cooperate with my Office on a whole range of important human rights issues -- which the previous Government had absolutely refused to do -- and I need to engage with them to ensure those commitments translate into reality,” Al Hussein said in the statement, adding that the deferral of the report was “for one time only.”

“I give my personal, absolute and unshakable commitment that the report will be published by September … I want this report to have the maximum possible impact in ensuring a genuine and credible process of accountability and reconciliation in which the rights of victims to truth, justice and reparations are finally respected,” Al Hussein added.