It said Chilcott's remark at a public speech Monday that aspirations by minority Tamil Tiger rebels for a separate state of Tamil Eelam were not illegitimate was unacceptable to the government.
Foreign Ministry Secretary Palitha Kohona expressed the government's "deep concern" over the remarks.
"(Kohona) stated that this statement was unacceptable to the Government of Sri Lanka given the British government's categorical rejection of the creation of a separate state in Sri Lanka," the ministry statement said.
The statement said the British High Commissioner "categorically confirmed" that the UK does not support in any way the establishment of a separate state in Sri Lanka.
"The British High Commissioner by way of explanation