United Nations (PTI): A group of United Nations' independent experts has asked the Human Rights Council to urgently set up an international inquiry to address the "critical" situation in Sri Lanka.

"There is an urgent need to establish an international commission of inquiry to document the events of recent months and to monitor ongoing developments," the UN experts dealing with summary executions, right to health, right to food and water and sanitation said in a joint statement.

"The current humanitarian crisis in Sri Lanka gives cause for deep concern, not only in terms of the number of civilians who have been and continue to be killed, but because of a dramatic lack of transparency and accountability," the experts- Philip Alston, Anand Grover, Olivier De Schutter and Catarina de Albuquerque- said in the statement.

There is a good reason to believe that thousands of civilians have been killed in the past three months alone, and still the Sri Lankan government is yet to account for the casualties, or to allow journalists and humanitarian monitors in the war zone, UN expert on summary executions Alston said.