Responding to a petition signed by over 10,000 British citizens calling for Sri Lanka to be referred to the International Criminal Court, the UK government said that "international criminal justice and accountability is a fundamental element", however maintained that the UN Human Rights Council resolutions were the best way of acheiving accountability. 

The petition urged "Refer Sri Lanka to International Criminal Court, if it continues to fail to implement its commitment made to the UNHRC Res. [A/HRC/RES/30/1] by March 2019". Read more here. 

In its response, the UK noted however that more needs to be done" by Sri Lanka and it should establish a "credible mechanisms for transitional justice."

Read full response below from the Foreign & Commonwealth Office: 

UK support for international criminal justice and accountability is a fundamental element of our foreign policy. The UK supports Sri Lanka’s accountability commitments to the UN Human Rights Council through Resolutions 30/1 and 34/1 as the best way to establish truth, and to achieve justice, restitution and reconciliation. A national process, initiated by the Government of Sri Lanka and supported by all communities, offers the best route to achieve this.

The UK welcomed the Annual Report of the Office of the UN High Commissioner for Human Rights on 21 March, which assessed progress made by the Sri Lankan government in the implementation of UN Human Rights Council resolution 30/1 and 34/1, and found that the Government of Sri Lanka has taken some steps to address human rights concerns and to introduce more democratic and accountable government.

These include the return of some military-held civilian land, the establishment of an Office of Missing Persons and the ratification of the Convention on Enforced Disappearances. However, more needs to be done. We are encouraging further progress on these issues, as well as encouraging the Government of Sri Lanka to deliver meaningful devolution through constitutional reform, and to establish credible mechanisms for transitional justice. Minister for Asia and the Pacific Mark Field raised these issues with the Government of Sri Lanka during his visit in October, and subsequently made three public statements – on 26 and 29 October, and 9 November – urging Sri Lanka to fully implement the commitments it has made to the UN Human Rights Council.

The UK is committed to supporting the Sri Lankan Government’s efforts to improve the human rights situation in the country. The UK is providing Sri Lanka with £8.3 million of Conflict, Stability and Security Fund funding over three years, including support for police reform and training, reconciliation and peace building, and resettlement and demining in the north of the country.