In my experience, it's much more complex than Asia = mostly en_GB and Europe = mostly en_US.

Going by the accents I hear in my (undergraduate ESL) classrooms in Austria, of the accents which are discernibly vaguely resembling of a native accent (British, American, etc), you'll certainly hear both. There is a strong correlation between Western European students and British accents, and Eastern European students and American accents. Though of course there are an increasing number of Western European students who have American(ish) accents.

Why might his be? Could be many things, of course, though consider that the high-school ESL teachers in Western Europe were schooled when the only really accessible English-speaking country was the UK (think especially the difference in flight costs between then and now). Certainly the only school teachers I've met with anything close to a US accent were under 40. ESL took off in Eastern Europe primarily after the fall of the Iron Curtain. Many of the new ESL teachers in that region may have been American native-speakers. It was also a time when American culture reigned supreme (even us British children would put on American accents a lot during play).

As for Asia, my experience of (non-Hindi, southern) India was overwhelmingly British, as one would expect. Filipinos that I've met, however, spoke with overwhelmingly American accents. Colonial history will be the largest factor here, I assume.

One other thing to keep in mind is that it seems easier to 'cover' the non-native accent with American English than with British English. I have met very few Austrians who have managed to cover their Austrian accent with a Southern Standard British accent. It can be done, but few manage. Those who do have usually spent decades getting there. Conversely, I have met hundreds of young Austrians who have picked up an American accent in a matter of a month or two as an au pair in the US, or even a few weeks' holiday. Irish and Scottish accents also seem to be better than Southern Standard at 'covering' non-native accents.

So, no conclusive answers from me but hopefully some food for thought! I wish you the best with your research.

Thank you Hendrik Bower

What I said about Asia was that it is more complex than just Asia using mostly British English. How does that not apply to China? I'm not quite sure I understand your point.

Thanks a lot Christophe Strobbe. Your response is highly appreciated because of the informative content.

UK spelling is more common in the former British colonies (except USA), and is the standard used by the EU and the UN. Thus it is much more widely used in formal usage than US spelling. However, because US spelling is the default on most computer programs, it creeps into English usage all over.