"Football must play its part as an engine of integration and we back their appeal," Stephane Burchkalter, secretary general of FIFpro's African division told Watford's official website.
"We expect the government to favour the spirit of the law."
Hornets boss Aidy Boothroyd has already expressed his views on the decision to deport Bangura when he told BBC Radio 5 Live: "It is an incredible decision, absolutely ludicrous.
"We hear about things all the time where we vote to elect people to power and then we presume and hope that they will put civil servants in place who will do a good job.
"I hope common sense does prevail. We have the opportunity to appeal - we have 10 days to do that, which takes us up to Christmas. We will be appealing because we think it is a ridiculous decision.
"We hope to get other people in involved. The Home Secretary can get involved now. We are speaking to people through the club.
"We thought we could put our faith in British justice but obviously not. We have to keep trying everything we can to make sure he stays.
"To escape civil war twice and avoid what he has avoided in his life, we cannot imagine what this boy has gone through in his short life and then somebody somewhere thinks it is a good idea to send him back to all of that."