In an everyday modern context, burial ceremony wouldn't sound as idiomatic as funeral or memorial service, or graveside service, typically held shortly after the funeral. I might even wonder if it was a translation from a third language, perhaps from some non-Judeo-Christian culture where there are different traditions related to death, or referring to something like burial rituals in, say, an archaeological sense.
For someone like a head of state, the word ceremony suggests flags at half mast, military honors, etc., so that part makes sense enough, though in English ceremonies in the plural might be more idiomatic.
I agree, though, that burial isn't right if it did not take place at the cemetery. So as escoville says, if it was in fact the funeral (ceremonies), you should use that word instead. For a head of state, the usual term is state funeral.