There has been a server in Singapore several months ago but it wasn't very popular. I'm not sure if there's enough hashpower coming from this region to justify the cost and effort of running a server. I might do a one month trial sometime soon to check the demand.
I would go for a server in Korea, better speed than SG and closer to China.
My tests didn't agree with this, latency was worse for .kr than .sg, but anywhere closer than US is an improvement.