[hoaw]

You are unlikely to find a western labor union that is specifically pro immigration these days. Since labor has been in decline in the west for the last few decades. Before that I am sure you could find those who were pro labor immigration. The Nordic countries have for example had relatively large labor immigration under social democratic governments (which are usually associated with the labor unions).

Also it depends what you mean by pro immigration. No union is going to be pro liberal immigration rules, since they don't want to undermine their own members. For it make sense for a union it has to be employees who are lacking, either in numbers or skill, in the country and can therefor expand the country's share of the market.