The appeal was made in a communique signed by over 100 women and 20 organisations, seeking sustained focus on the plight of the women directly affected by the violence.

"We make this call as women who have been directly impacted by the violence and witnessed numerous domestic initiatives, including commissions of inquiry and other investigations, that have not led to holding perpetrators accountable," the women said in a statement.

"We say this having witnessed countless commissions and committees reportedly inquiring and investigating but a cloud of secrecy remains as to whether perpetrators were ever held accountable," they said.

The appeal has come after the new Sirisena government promised investigations via credible domestic processes.

Victims, survivors and affected communities took significant risks by submitting evidence to the Office of the High Commissioner for Human Rights Investigation on Sri Lanka (OISL) in the hope of justice and accountability, it said.

"We fear that a delay now in terms of the OISL is a denial of justice and a sign to perpetrators that impunity is acceptable," the women said.

They urged the Sri Lanka government to initiate a credible domestic process that includes components of truth telling and trials.

"In light of the short comings of the present framework, initiate immediate legal and policy reform to introduce processes that are independent and impartial and have the necessary resources and expertise to carry out investigations and inquiries among other measures," they said.

The new government has opted for a credible domestic investigation that will meet international standards.

However, the Tamil minority nationalist groups have stepped up pressure to make way for an international investigation as mandated by last year's UN Human Rights Council resolution on alleged war crimes committed by both the LTTE and the government troops.

According to UN estimates, more than 40,000 civilians were killed in Lanka during the final phase of the nearly three decades-long civil war that ended in 2009. The Sri Lankan government disputes the UN figure.