Foreign Minister Mangala Samaraweera has extended a formal invitation to UN Human Rights Commissioner Zeid Ra'ad Zeid Al-Hussein, to visit the country, the ministry sources said.
The report on Sri Lanka by the investigation team of the Office of the UN High Commissioner for Human Rights (OHCHR) will be taken up for discussion at the UN Human Rights Council in Geneva in March.
The former Mahinda Rajapaksa government had opposed the investigation and did not allow the UN investigators entry.
The new government led by Maithripala Sirisena has also pledged to continue with the same policy of non-cooperation but would engage UNHCR to set up a domestic investigation.
Tamil minority parties have expressed opposition for a domestic investigation.
The former government of Rajapaksa had hosted Al Hussein's predecessor Navy Pillay in 2013. Her conduct was criticised by the Rajapaksa government as biased against Sri Lanka.