"This sudden reaction raises grave doubts as to the objectivity and impartiality of their decision, and Sri Lankan authorities view S&P’s decision as being illogical, ill-advised and without rational basis or foundation."
The statement said authorities were "greatly surprised and disappointed" by the lowering of the stable outlook of Sri Lanka's 'B+' speculative rating to 'negative' earlier in the day.
"Such a change has been effected without any prior information or discussion with the Sri Lankan authorities," the Central Bank said.
"The reasons that have been attributed by S&P for the revision of outlook are also untenable."
The monetary authority said Sri Lanka