I think that the answer will almost certainly be in the national AIP.
I've flown in "metres" environments in GA, and found that you usually get a mixed fleet and somehow everybody copes with conversion tables and common sense. (Confuses the hell out of me, but then I'm a bear of little brain, and in the end, even I coped).
Does any country mandate metres in air transport? The only two I can think of who *might* are China and Russia, and both have unconverted western airliners going in and out regularly without incident. That said, both certainly have airports which are restricted to national aircraft only, so the rules may be different there.
G