The foreign ministry here said that 36 more countries had co-sponsored the resolution which was adopted without a vote. This was in addition to the original sponsors -- the US, UK, Montenegro and Macedonia.
Titled "Promoting reconciliation, accountability and human rights in Sri Lanka" the resolution gives Sri Lanka two years to show more progress on the transitional justice process.
Sri Lanka was granted 18 months by a UNHRC resolution in October 2015 to initiate a credible investigation into the nearly three-decades long civil war with the LTTE.
This includes engagement with special procedure mandate holders in protecting human rights, asking the UNHRC to provide advice and technical assistance.
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The two-year time has been allowed despite strong opposition from the Tamil lobby who cited inaction by the government to show genuine commitment to the resolution.
UN rights council had called for international judges to help investigate possible war crimes to guarantee impartiality.
Sri Lankan government has resisted the call by UN Human Rights chief Zeid Ra'ad Al Hussein to set up an international hybrid court.
Speaking at the sessions, the Sri Lankan deputy foreign minister Harsha de Silva said, "It is always work-in-progress. The people of Sri Lanka have been through extremely difficult and painful times, and although much has been done, there is much still left to do, including strengthening our institutions and achieving economic progress. There are multiple challenges that we face."
According to the UN figures, up to 40,000 civilians were killed by the security forces during former president Mahinda Rajapaksa's regime that brought an end to the conflict with the defeat of LTTE in 2009.