Being fired when ill for too long

A friend of mine has fallen sick and needs to undergo medical treatment for several months. He is currently being employed by the local office (in Taipei) of a big international company but I assume this situation falls under the local laws.

I guess that an employer does have the right to release (to put it nicely) an employee when he is sick for too long, something which isn’t nice but perhaps understandable from their point of view.

So is there any such law or regulation here?

If yes, what is the time frame your are allowed of being sick before being fired?

At this time I also urge all expats to arrange for an additional insurance if you don’t have any yet which will cover medical expenses here and overseas with the guarantee of infinite treatment.
The national health insurance in Germany where he currently undergoes treatment does not take him back (not employed there and sick, either argument allows to reject him) and by end of this year he will not only loose his current insurance cover but even his job as his contract will expire then. By that also the insurance provided by his company will cancel his membership and cease his salary payments (which they do anyway after 3 months as stipulated in their policy).