The UN has agreed to Sri Lanka's request to delay a long-awaited report into alleged atrocities committed during Sri Lanka's 26-year civil war.
The UN rights chief said he recommended the deferral of the report until September "to allow for a stronger and more comprehensive report".
He said Sri Lanka's new government was far more prepared to co-operate on the issue than the previous administration.
Sri Lanka's army defeated Tamil Tiger separatist rebels in May 2009.
Both sides have been accused of committing war crimes and the UN report had been originally due next month.
Maithripala Sirisena defeated long-time ruler Mahinda Rajapaksa in presidential elections last month, and promised to co-operate with the UN.
UN High Commissioner for Human Rights Zeid Ra'ad Al Hussein said Mr Sirisena had given clear commitments indicating it was prepared to co-operate "on a whole range of important human rights issues - which the previous government had absolutely refused to do".
"I need to engage with them to ensure those commitments translate into reality" he said.
He said he had recommended the report's deferral to reflect "the changing context in Sri Lanka, and the possibility that important new information may emerge which will strengthen the report".
But he stressed that those responsible for committing abuses would not escape justice.
"I am acutely aware that many victims... might see this is as the first step towards shelving, or diluting, a report they have long feared they would never see," he said.